Вправи: 47

47. Обчисліть:

1) 1216 + 823 = 1216 + 846 = 2056;

2) 1618 + 256 = 16 + 2 + (1\38 + 5\46) = 18 + 3+2024 = 18 + 2324 = 182324;

3) 7 – 2313 = 61313 – 2313 = (6 – 2) + (1313 – 1313) = 4 + 1013 = 41013;

4) 8110 – 523 = (8 – 5) + (1\310 – 2\103) = 3 + (330 – 2030) = 2 + (3330 – 2030) =

= 21330.

5) 213 • 314 = 73 • 314 = 714 = 12;

6) 525 • 313 = 275 • 103 = 91 • 21 = 181 = 18;

7) 234 : 138 = 114 : 118 = 114 • 811 = 84 = 2;

8) 310 : 245 = 310 : 145 = 310 • 514 = 32 • 114 = 328.