General rule for rounding off

Transcript

General rule for rounding off General rule says For a number in tens, we round off to tens. For a number in hundred, we round off to hundred. For a number in thousands, we round off to thousands. Eg: 479 × 81 According to general rule, 479 is rounded off to nearest hundred ∴ 479 → 500 81 is rounded off to nearest ten ∴ 81 → 80 So, Estimated Product = 500 × 80 = 5 × 100 × 8 × 10 = (5 × 8) × 1000 = 40 × 1000 = 40000