53. 651 + 126; 379 − 253; 306 − 138; 402 − 243; 453 · 2; 321 · 3; 5 · 171; 6 · 98

1. \(651 + 126 = 777\)
2. \(379 - 253 = 126\)
3. \(306 - 138 = 168\)
4. \(402 - 243 = 159\)
5. \(453 \cdot 2 = 906\)
6. \(321 \cdot 3 = 963\)
7. \(5 \cdot 171 = 855\)
8. \(6 \cdot 98 = 588\)

Ответ: 777; 126; 168; 159; 906; 963; 855; 588.