Rounding Numbers to 10 and 100

Why Do We Round Numbers?

Shopping: £47.89 becomes about £50 Distances: 284 miles becomes about 300 miles Time: 23 minutes becomes about 20 minutes Makes mental calculations easier Helps us estimate and check answers

The Golden Rounding Rule

5 or more, up you go! 4 or less, stay down low!

Rounding to the Nearest 10

Look at the ones digit (units place) If it's 0, 1, 2, 3, or 4 → round DOWN If it's 5, 6, 7, 8, or 9 → round UP Example: 47 → 50 (7 is ≥ 5) Example: 23 → 20 (3 is < 5)

Quick Practice: Round to 10

Round these numbers to the nearest 10: 26 → ? 73 → ? 85 → ? 41 → ? Write your answers on mini-whiteboards!

Rounding to the Nearest 100

Look at the tens digit If it's 0, 1, 2, 3, or 4 → round DOWN If it's 5, 6, 7, 8, or 9 → round UP Example: 347 → 300 (4 in tens place) Example: 286 → 300 (8 in tens place)

Rounding Challenge

Round to nearest 10 AND nearest 100: Number: 267 To nearest 10: ___ To nearest 100: ___ Number: 834 To nearest 10: ___ To nearest 100: ___

Success Check

✓ I can identify which digit to look at ✓ I can round whole numbers to nearest 10 ✓ I can round whole numbers to nearest 100 ✓ I understand why rounding is useful Next: Practice worksheets and real-world problems!