Частина 1. Номер 623

Виконай дії зручним способом.

357 – 249 = 357 – 350 + 1 = 107 + 1 = 108;

425 + 351 = 425 + 300 + 50 + 1 = 725 + 50 + 1 = 775 + 1 = 776;

122 + 155 = 122 + 100 + 50 + 5 = 222 + 50 + 5 = 272 + 5 = 277;

800 – 494 = 800 – 500 + 6 = 300 + 6 = 306;

800 – 300 – 125 = 800 – 300 – 100 – 20 – 5 = 500 – 100 – 20 – 5 = 375;

500 – (180 – 77) = 500 – (180 – 80 + 3) = 500 – (100 + 3) = 500 – 100 – 3 = 397.