Завдання:
Обчисли зручним способом:
1) 742 + 39 + 58;
2) 973 + 115 – 273;
3) 832 – 15 – 32;
4) 2 ⋅ 115 ⋅ 50;
5) 29 ⋅ 19 + 71 ⋅ 19;
6) 192 ⋅ 37 – 92 ⋅ 37.
Розв'язок:
1) 742 + 39 + 58 = (742 + 58) + 39 = 800 + 39 = 839;
2) 973 + 115 – 273 = (973 - 273) + 115 = 700 + 115 = 815;
3) 832 – 15 – 32 = (832 - 32) - 15 = 800 - 15 = 785;
4) 2 ⋅ 115 ⋅ 50 = (2 • 50) • 115 = 100 • 115 = 11 500;
5) 29 ⋅ 19 + 71 ⋅ 19 = 19 • (29 + 71) = 19 • 100 = 1900;
6) 192 ⋅ 37 – 92 ⋅ 37 = 37 • (192 - 92) = 37 • 100 = 3700.