{"id":488,"date":"2026-06-23T15:17:15","date_gmt":"2026-06-23T06:17:15","guid":{"rendered":"https:\/\/www.risu-japan.com\/drill\/?p=488"},"modified":"2026-06-23T15:17:15","modified_gmt":"2026-06-23T06:17:15","slug":"mental-arithmetic-2digit","status":"publish","type":"drill","link":"https:\/\/www.risu-japan.com\/drill\/grade2\/calculation-tricks\/mental-arithmetic-2digit\/","title":{"rendered":"2\u30b1\u30bf\u306e\u8db3\u3057\u7b97\u30fb\u5f15\u304d\u7b97\u306e\u6697\u7b97"},"content":{"rendered":"

<\/p>\n

2\u30b1\u30bf\u306e \u6697\u7b97\u3068\u306f<\/h2>\n

\u300c35<\/mn>+<\/mo>24<\/mn><\/math><\/span>\u300d\u3084\u300c68<\/mn>–<\/mo>25<\/mn><\/math><\/span>\u300d\u306e\u3088\u3046\u306a2\u6841\u306e\u8a08\u7b97\u3092\u3001\u7b46\u7b97\u3092\u66f8\u304b\u305a\u306b\u982d\u306e\u4e2d\u3060\u3051\u3067\u8a08\u7b97\uff08\u6697\u7b97\uff1a\u3042\u3093\u3056\u3093\uff09\u3059\u308b\u65b9\u6cd5\u3092\u5b66\u3073\u307e\u3059\u3002\u8db3\u3057\u7b97\u3067\u3082\u5f15\u304d\u7b97\u3067\u3082\u3001\u6697\u7b97\u306e\u6700\u5927\u306e\u30b3\u30c4\u306f\u3001\u6570\u3092\u300c\u5341\u306e\u307e\u3068\u307e\u308a\u300d\u3068\u300c\u4e00\u306e\u3070\u3089\u3070\u3089\u300d\u306b\u5206\u3051\u3066\u8003\u3048\u308b\u3053\u3068\u3067\u3059\u3002\u7b46\u7b97\u306f\u300c\u4e00\u306e\u4f4d\u300d\u304b\u3089\u8a08\u7b97\u3057\u307e\u3059\u304c\u3001\u6697\u7b97\u3067\u306f\u982d\u306e\u4e2d\u304c\u6574\u7406\u3057\u3084\u3059\u3044\u3088\u3046\u306b\u300c\u5927\u304d\u306a\u4f4d\uff08\u5341\u306e\u4f4d\uff09\u300d\u304b\u3089\u9806\u756a\u306b\u51e6\u7406\u3057\u3066\u3044\u304f\u306e\u304c\u4e00\u822c\u7684\u3067\u3059\u3002<\/p>\n

\u6697\u7b97\u306e\u30eb\u30fc\u30eb<\/h2>\n

1. \u6570\u3092\u4f4d\u3054\u3068\u306b\u5206\u3051\u308b<\/h3>\n

\u982d\u306e\u4e2d\u3067\u3001\u8a08\u7b97\u3059\u308b\u6570\u3092\u300c\u5341\u306e\u4f4d\u300d\u3068\u300c\u4e00\u306e\u4f4d\u300d\u306b\u5206\u3051\u307e\u3059\u3002\uff08\u4f8b\uff1a24<\/mn><\/math><\/span> \u306f 20<\/mn><\/math><\/span> \u3068 4<\/mn><\/math><\/span>\uff09<\/p>\n

2. \u8db3\u3057\u7b97\u306e\u3084\u308a\u65b9<\/h3>\n

\u5341\u306e\u4f4d\u3069\u3046\u3057\u3001\u4e00\u306e\u4f4d\u3069\u3046\u3057\u3092\u8db3\u3057\u3066\u3001\u6700\u5f8c\u306b\u5408\u308f\u305b\u307e\u3059\u3002\uff08\u4f8b\uff1a35<\/mn>+<\/mo>24<\/mn><\/math><\/span> \u306a\u3089\u300130<\/mn>+<\/mo>20<\/mn>=<\/mo>50<\/mn><\/math><\/span>\u30015<\/mn>+<\/mo>4<\/mn>=<\/mo>9<\/mn><\/math><\/span>\u3001\u5408\u308f\u305b\u3066 59<\/mn><\/math><\/span>\uff09<\/p>\n

3. \u5f15\u304d\u7b97\u306e\u3084\u308a\u65b9<\/h3>\n

\u5f15\u304b\u308c\u308b\u6570\u304b\u3089\u3001\u5148\u306b\u300c\u5341\u306e\u4f4d\u300d\u3092\u5f15\u304d\u3001\u6b8b\u3063\u305f\u6570\u304b\u3089\u300c\u4e00\u306e\u4f4d\u300d\u3092\u5f15\u304d\u307e\u3059\u3002\uff08\u4f8b\uff1a68<\/mn>–<\/mo>25<\/mn><\/math><\/span> \u306a\u3089\u300168<\/mn>–<\/mo>20<\/mn>=<\/mo>48<\/mn><\/math><\/span>\u300148<\/mn>–<\/mo>5<\/mn>=<\/mo>43<\/mn><\/math><\/span>\uff09<\/p>\n

4. \u81ea\u5206\u306e\u3084\u308a\u65b9\u3092\u898b\u3064\u3051\u308b<\/h3>\n

\u81ea\u5206\u304c\u982d\u306e\u4e2d\u3067\u8003\u3048\u3084\u3059\u3044\uff08\u899a\u3048\u3084\u3059\u3044\uff09\u3084\u308a\u65b9\u3092\u898b\u3064\u3051\u3066\u8a08\u7b97\u3057\u307e\u3057\u3087\u3046\u3002<\/p>\n

<\/p>\n

\n

\u4f8b\u984c<\/h2>\n
\n

\u554f1<\/h3>\n

\u982d\u306e \u4e2d\u3067 \u8a08\u7b97\u3057\u307e\u3057\u3087\u3046\u3002<\/p>\n

42<\/mn>+<\/mo>15<\/mn>=<\/mo><\/math><\/div>\n<\/p><\/div>\n
\n

\u554f2<\/h3>\n

\u982d\u306e \u4e2d\u3067 \u8a08\u7b97\u3057\u307e\u3057\u3087\u3046\u3002<\/p>\n

76<\/mn>–<\/mo>34<\/mn>=<\/mo><\/math><\/div>\n<\/p><\/div>\n
\n

\u89e3\u8aac<\/h3>\n
\n

\u554f1<\/h4>\n

\u6697\u7b97\u3092\u3057\u3066\u307f\u307e\u3057\u3087\u3046\u3002\u8db3\u3057\u7b97\u306f\u7e70\u308a\u4e0a\u304c\u308a\u306e\u6709\u7121\u306b\u304b\u304b\u308f\u3089\u305a\u5341\u306e\u4f4d\u3068\u4e00\u306e\u4f4d\u540c\u58eb\u3067\u9806\u756a\u306b\u8a08\u7b97\u3092\u3059\u308b\u3053\u3068\u3067\u6c42\u3081\u3089\u308c\u307e\u3059\u3002\u305d\u308c\u305e\u308c\u306e\u4f4d\u3054\u3068\u306b\u8db3\u3057\u7b97\u3092\u3059\u308b\u3068\u3001\u5341\u306e\u4f4d\u306f 40<\/mn>+<\/mo>10<\/mn>=<\/mo>50<\/mn><\/math><\/span>\u3001\u4e00\u306e\u4f4d\u306f 2<\/mn>+<\/mo>5<\/mn>=<\/mo>7<\/mn><\/math><\/span> \u306a\u306e\u3067\u5408\u308f\u305b\u3066 57<\/mn><\/math><\/span> \u3068\u306a\u308a\u307e\u3059\u3002<\/p>\n

\u7b54\u3048\uff1a57<\/p>\n<\/p><\/div>\n

\n

\u554f2<\/h4>\n

\u5f15\u304d\u7b97\u3082\u6697\u7b97\u3067\u89e3\u3044\u3066\u307f\u307e\u3057\u3087\u3046\u3002\u4eca\u56de\u306f\u7e70\u308a\u4e0b\u304c\u308a\u304c\u306a\u3044\u3053\u3068\u304c\u5206\u304b\u308b\u306e\u3067\u5341\u306e\u4f4d\u3068\u4e00\u306e\u4f4d\u540c\u58eb\u3067\u9806\u756a\u306b\u8a08\u7b97\u3092\u3057\u3066\u307f\u307e\u3059\u3002\u5341\u306e\u4f4d\u306f 70<\/mn>–<\/mo>30<\/mn>=<\/mo>40<\/mn><\/math><\/span>\u3001\u4e00\u306e\u4f4d\u306f 6<\/mn>–<\/mo>4<\/mn>=<\/mo>2<\/mn><\/math><\/span> \u306a\u306e\u3067\u5408\u308f\u305b\u3066 42<\/mn><\/math><\/span> \u3068\u306a\u308a\u307e\u3059\u3002<\/p>\n

\u7b54\u3048\uff1a42<\/p>\n<\/p><\/div>\n<\/p><\/div>\n<\/section>\n

<\/p>\n

\n

\u7df4\u7fd2\u554f\u984c<\/h2>\n
\n

\u554f1<\/h3>\n

\u982d\u306e \u4e2d\u3067 \u8a08\u7b97\u3057\u307e\u3057\u3087\u3046\u3002<\/p>\n

27<\/mn>+<\/mo>15<\/mn>=<\/mo><\/math><\/div>\n<\/p><\/div>\n
\n

\u554f2<\/h3>\n

\u982d\u306e \u4e2d\u3067 \u8a08\u7b97\u3057\u307e\u3057\u3087\u3046\u3002<\/p>\n

63<\/mn>–<\/mo>26<\/mn>=<\/mo><\/math><\/div>\n<\/p><\/div>\n
\n

\u554f3<\/h3>\n

\u304d\u306e\u3046 \u672c\u3092 24<\/mn><\/math><\/span> \u30da\u30fc\u30b8\u3001\u4eca\u65e5 18<\/mn><\/math><\/span> \u30da\u30fc\u30b8 \u8aad\u307f\u307e\u3057\u305f\u3002\u305c\u3093\u3076\u3067 \u4f55\u30da\u30fc\u30b8 \u8aad\u307f\u307e\u3057\u305f\u304b\u3002\u3057\u304d\u3092 \u3064\u304f\u3063\u3066 \u982d\u306e\u4e2d\u3067 \u8a08\u7b97\u3057\u307e\u3057\u3087\u3046\u3002<\/p>\n<\/p><\/div>\n<\/section>\n

<\/p>\n

\n

\u5fdc\u7528\u554f\u984c<\/h2>\n
\n

\u554f1<\/h3>\n

\u982d\u306e \u4e2d\u3067 \u8a08\u7b97\u3057\u307e\u3057\u3087\u3046\u3002<\/p>\n

15<\/mn>+<\/mo>15<\/mn>+<\/mo>15<\/mn>=<\/mo><\/math><\/div>\n<\/p><\/div>\n
\n

\u554f2<\/h3>\n

\u982d\u306e \u4e2d\u3067 \u8a08\u7b97\u3057\u307e\u3057\u3087\u3046\u3002<\/p>\n

100<\/mn>–<\/mo>45<\/mn>=<\/mo><\/math><\/div>\n<\/p><\/div>\n
\n

\u554f3<\/h3>\n

\u25a1 \u306b \u5165\u308b \u6570\u3092 \u6697\u7b97\u3067 \u898b\u3064\u3051\u307e\u3057\u3087\u3046\u3002<\/p>\n

20<\/mn>+<\/mo>\u25a1<\/mi>=<\/mo>60<\/mn><\/math><\/div>\n<\/p><\/div>\n<\/section>\n

<\/p>\n

\n

\u89e3\u7b54\u3068\u89e3\u8aac<\/h2>\n
\n

\u7df4\u7fd2\u554f\u984c<\/h3>\n
\n

\u554f1<\/h4>\n

\u7e70\u308a\u4e0a\u304c\u308a\u306e\u3042\u308b\u8db3\u3057\u7b97\u3082\u4eca\u307e\u3067\u3068\u540c\u3058\u3088\u3046\u306b\u4f4d\u3054\u3068\u306b\u8a08\u7b97\u3092\u3057\u3066\u6c42\u3081\u3066\u307f\u307e\u3057\u3087\u3046\u3002\u305d\u308c\u305e\u308c\u306e\u4f4d\u3054\u3068\u306b\u8db3\u3057\u7b97\u3092\u3059\u308b\u3068\u3001\u5341\u306e\u4f4d\u306f 20<\/mn>+<\/mo>10<\/mn>=<\/mo>30<\/mn><\/math><\/span>\u3001\u4e00\u306e\u4f4d\u306f 7<\/mn>+<\/mo>5<\/mn>=<\/mo>12<\/mn><\/math><\/span> \u306a\u306e\u3067\u5408\u308f\u305b\u3066 42<\/mn><\/math><\/span> \u3068\u306a\u308a\u307e\u3059\u3002<\/p>\n

\u7b54\u3048\uff1a42<\/p>\n<\/p><\/div>\n

\n

\u554f2<\/h4>\n

\u7e70\u308a\u4e0b\u304c\u308a\u306e\u3042\u308b\u5f15\u304d\u7b97\u306f\u5de5\u592b\u3057\u3066\u8003\u3048\u308b\u5fc5\u8981\u304c\u3042\u308a\u307e\u3059\u3002\u307e\u305a\u306f\u5f15\u304f\u6570\u3092 20<\/mn><\/math><\/span> \u3068 6<\/mn><\/math><\/span> \u306b\u5206\u3051\u3066\u307f\u307e\u3057\u3087\u3046\u3002\u305d\u3057\u3066\u305d\u308c\u305e\u308c\u3092\u5f15\u304d\u7b97\u3057\u3066\u307f\u307e\u3059\u300263<\/mn>–<\/mo>20<\/mn>=<\/mo>43<\/mn><\/math><\/span>\u300143<\/mn>–<\/mo>6<\/mn>=<\/mo>37<\/mn><\/math><\/span>\u3002\u3088\u3063\u3066\u7b54\u3048\u306f 37<\/mn><\/math><\/span> \u3068\u306a\u308a\u307e\u3059\u3002<\/p>\n

\u7b54\u3048\uff1a37<\/p>\n<\/p><\/div>\n

\n

\u554f3<\/h4>\n

\u6628\u65e5\u3068\u4eca\u65e5\u3067 24<\/mn><\/math><\/span> \u30da\u30fc\u30b8\u3068 18<\/mn><\/math><\/span> \u30da\u30fc\u30b8\u8aad\u3093\u3060\u306e\u3067\u3001\u3053\u308c\u3089\u3092\u8db3\u3057\u5408\u308f\u305b\u3066\u307f\u307e\u3057\u3087\u3046\u3002\u305d\u308c\u305e\u308c\u306e\u4f4d\u3054\u3068\u306b\u8db3\u3057\u7b97\u3092\u3059\u308b\u3068\u3001\u5341\u306e\u4f4d\u306f 20<\/mn>+<\/mo>10<\/mn>=<\/mo>30<\/mn><\/math><\/span>\u3001\u4e00\u306e\u4f4d\u306f 4<\/mn>+<\/mo>8<\/mn>=<\/mo>12<\/mn><\/math><\/span> \u306a\u306e\u3067\u5408\u308f\u305b\u3066 42<\/mn><\/math><\/span> \u3068\u306a\u308a\u307e\u3059\u3002\u3088\u3063\u3066\u7b54\u3048\u306f 42<\/mn><\/math><\/span> \u30da\u30fc\u30b8\u3067\u3059\u3002<\/p>\n

\u7b54\u3048\uff1a42\u30da\u30fc\u30b8<\/p>\n<\/p><\/div>\n<\/p><\/div>\n

\n

\u5fdc\u7528\u554f\u984c<\/h3>\n
\n

\u554f1<\/h4>\n

3\u3064\u306e\u8db3\u3057\u7b97\u306e\u5834\u5408\u3082\u5de6\u304b\u3089\u9806\u756a\u306b\u6697\u7b97\u3092\u3057\u3066\u307f\u307e\u3057\u3087\u3046\u3002\u307e\u305a\u306f 15<\/mn>+<\/mo>15<\/mn><\/math><\/span> \u3092\u8a08\u7b97\u3057\u3066\u307f\u307e\u3059\u3002\u305d\u308c\u305e\u308c\u306e\u4f4d\u3054\u3068\u306b\u8db3\u3057\u7b97\u3092\u3059\u308b\u3068\u3001\u5341\u306e\u4f4d\u306f 10<\/mn>+<\/mo>10<\/mn>=<\/mo>20<\/mn><\/math><\/span>\u3001\u4e00\u306e\u4f4d\u306f 5<\/mn>+<\/mo>5<\/mn>=<\/mo>10<\/mn><\/math><\/span> \u306a\u306e\u3067\u5408\u308f\u305b\u3066 30<\/mn><\/math><\/span> \u3068\u306a\u308a\u307e\u3059\u3002\u6b21\u306b 30<\/mn>+<\/mo>15<\/mn><\/math><\/span> \u3092\u8a08\u7b97\u3057\u3066\u307f\u307e\u3059\u3002\u5341\u306e\u4f4d\u306f 30<\/mn>+<\/mo>10<\/mn>=<\/mo>40<\/mn><\/math><\/span>\u3001\u4e00\u306e\u4f4d\u306f 0<\/mn>+<\/mo>5<\/mn>=<\/mo>5<\/mn><\/math><\/span> \u306a\u306e\u3067\u5408\u308f\u305b\u3066 45<\/mn><\/math><\/span> \u3068\u306a\u308a\u307e\u3059\u3002\u3088\u3063\u3066\u7b54\u3048\u306f 45<\/mn><\/math><\/span> \u3067\u3059\u3002<\/p>\n

\u7b54\u3048\uff1a45<\/p>\n<\/p><\/div>\n

\n

\u554f2<\/h4>\n

\u5de5\u592b\u3057\u3066\u7e70\u308a\u4e0b\u304c\u308a\u306e\u3042\u308b\u5f15\u304d\u7b97\u3092\u8003\u3048\u3066\u307f\u307e\u3057\u3087\u3046\u300245<\/mn><\/math><\/span> \u3092 40<\/mn><\/math><\/span> \u3068 5<\/mn><\/math><\/span> \u306b\u5206\u3051\u3066\u305d\u308c\u305e\u308c\u3092\u5f15\u304d\u7b97\u3057\u3066\u307f\u307e\u3059\u3002100<\/mn>–<\/mo>40<\/mn>=<\/mo>60<\/mn><\/math><\/span>\u300160<\/mn>–<\/mo>5<\/mn>=<\/mo>55<\/mn><\/math><\/span>\u3002\u3088\u3063\u3066\u7b54\u3048\u306f 55<\/mn><\/math><\/span> \u3068\u306a\u308a\u307e\u3059\u3002\u3053\u306e\u3088\u3046\u306b2\u56de\u7e70\u308a\u4e0b\u304c\u308b\u5f15\u304d\u7b97\u3082\u5f15\u304f\u6570\u3092\u5206\u3051\u308b\u3053\u3068\u306b\u3088\u3063\u3066\u6c42\u3081\u3066\u307f\u307e\u3057\u3087\u3046\u3002<\/p>\n

\u7b54\u3048\uff1a55<\/p>\n<\/p><\/div>\n

\n

\u554f3<\/h4>\n

\u4eca\u56de\u306f\u8db3\u3055\u308c\u308b\u6570\u3082\u7b54\u3048\u3082\u3069\u3061\u3089\u3082\u4e00\u306e\u4f4d\u304c\u300c0<\/mn><\/math><\/span>\u300d\u3068\u306a\u3063\u3066\u3044\u307e\u3059\u306d\u3002\u3088\u3063\u3066 0<\/mn><\/math><\/span> \u306b\u4f55\u304b\u3092\u8db3\u3057\u3066 0<\/mn><\/math><\/span> \u306b\u306a\u308b\u306e\u306f 0<\/mn><\/math><\/span> \u306e\u6642\u306e\u307f\u306a\u306e\u3067\u3001\u7b54\u3048\u306e\u4e00\u306e\u4f4d\u306f\u300c0<\/mn><\/math><\/span>\u300d\u3068\u306a\u308b\u3053\u3068\u304c\u5206\u304b\u308a\u307e\u3059\u3002\u3088\u3063\u3066\u5341\u306e\u4f4d\u306e\u307f\u306b\u6ce8\u76ee\u3057\u3066\u8003\u3048\u3066\u307f\u307e\u3057\u3087\u3046\u3002\u5341\u306e\u4f4d\u306f 2<\/mn>+<\/mo>\u25a1<\/mi>=<\/mo>6<\/mn><\/math><\/span> \u306e\u8db3\u3057\u7b97\u3068\u8003\u3048\u3089\u308c\u307e\u3059\u3002\u3053\u306e\u3068\u304d \u25a1<\/mi><\/math><\/span> \u306b\u5f53\u3066\u306f\u307e\u308b\u306e\u306f 4<\/mn><\/math><\/span> \u306a\u306e\u3067\u3001\u7b54\u3048\u306f 40<\/mn><\/math><\/span> \u3068\u5206\u304b\u308a\u307e\u3059\u3002<\/p>\n

\u7b54\u3048\uff1a40<\/p>\n<\/p><\/div>\n<\/p><\/div>\n<\/section>\n

<\/p>\n