Реши примеры: 32 458 - 8 = 958 - 8 = 689 - 600 = 763 - 700 = 540 - 1 - 30 = 200 + 40 + 1 = 572 - 70 = 513 - 10 = 200 - 1 - 100 = 927 - 7 = 639 - 9 = 429 + 1 + 7 = 742 - 40 = 431 - 400 = 900 + 30 + 6 = 365 - 60 = 835 - 30 = 375 - 300, 375 - 70, 375 - 5 548 - 8 = 815 - 800 = 729 - 20 = 725 - 20 + 60 978 - 900 = 394 - 4 = 800 + 40 + 7 = 496 - 400 = 294 - 200 = 500 - 1 - 400 356 - 6 = 627 - 7 = 948 - 900 + 20 800 - 1 - 90 = 600 - 1 - 9 = 375-70 375-300=75 375-5=370 300 70 5 300 70 5 300 70 5

Устные приемы сложения и вычитания

1. Вычитание двузначных чисел:

• \( 458 - 8 = 450 \)
• \( 958 - 8 = 950 \)
• \( 689 - 600 = 89 \)
• \( 763 - 700 = 63 \)
• \( 540 - 1 - 30 = 539 - 30 = 509 \)
• \( 200 + 40 + 1 = 241 \)
• \( 572 - 70 = 502 \)
• \( 513 - 10 = 503 \)
• \( 200 - 1 - 100 = 199 - 100 = 99 \)
• \( 927 - 7 = 920 \)
• \( 639 - 9 = 630 \)
• \( 429 + 1 + 7 = 430 + 7 = 437 \)
• \( 742 - 40 = 702 \)
• \( 431 - 400 = 31 \)
• \( 900 + 30 + 6 = 936 \)
• \( 365 - 60 = 305 \)
• \( 835 - 30 = 805 \)
• \( 548 - 8 = 540 \)
• \( 815 - 800 = 15 \)
• \( 729 - 20 = 709 \)
• \( 978 - 900 = 78 \)
• \( 394 - 4 = 390 \)
• \( 496 - 400 = 96 \)
• \( 294 - 200 = 94 \)
• \( 356 - 6 = 350 \)
• \( 627 - 7 = 620 \)
• \( 540 - 1 - 30 = 509 \)

2. Примеры на сложение и вычитание круглых чисел:

• \( 375 - 300 = 75 \)
• \( 375 - 70 = 305 \)
• \( 375 - 5 = 370 \)
• \( 725 - 20 + 60 = 705 + 60 = 765 \)
• \( 800 + 40 + 7 = 847 \)
• \( 948 - 900 + 20 = 48 + 20 = 68 \)
• \( 800 - 1 - 90 = 799 - 90 = 709 \)
• \( 600 - 1 - 9 = 599 - 9 = 590 \)
• \( 500 - 1 - 400 = 499 - 400 = 99 \)

Ответ: 450, 950, 89, 63, 509, 241, 502, 503, 99, 920, 630, 437, 702, 31, 936, 305, 805, 540, 15, 709, 78, 390, 96, 94, 350, 620, 509; 75, 305, 370, 765, 847, 68, 709, 590, 99.