Let’s do an example


Round off 56 374 to the nearest 10, 100 and 1 000. 56 374: tens digit = 7; units digit = 4; write: 56 374 ≈ 56 370 56 374: hundreds digit = 3; tens digit = 7; write: 56 374 ≈ 56 400 56 374: thousands digit = 6; hundreds digit = 3; write 56 374 ≈ 56 000


Activity 1


Estimate each answer by rounding off to the nearest 1 000. 1 12 504 + 3 299 4 48 765 + 4 499


2 25 701 + 5 738 5 61 932 + 6 060


Solve addition sums


You can break down 5-digit whole numbers into ten thousands, thousands, hundreds, tens and units.


Let’s do an example


Calculate 52 376 + 39 687 by first estimating the answer by rounding off to the nearest 1 000: 52 376 + 39 687 ≈ 52 000 + 40 000 ≈ 92 000 Method 1: Adding in rows To add in rows, break down both numbers and write ten thousands, thousands, hundreds, tens and units in one row: 52 376 + 39 687


= 50 000 + 2 000 + 300 + 70 + 6 + 30 000 + 9 000 + 600 + 80 + 7 = 50 000 + 30 000 + 2 000 + 9 000 + 300 + 600 + 70 + 80 + 6 + 7 = 80 000 + 11 000 + 900 + 150 + 13 = 90 000 + 1 000 + 1 000 + 60 + 3 = 92 063


3 36 807 + 8 501 6 97 001 + 9 701


(break down; group) (add) (build up the answer)


Method 2: Adding in columns To add in columns, write ten thousands below ten thousands, thousands below thousands, hundreds below hundreds, tens below tens and units below units.


96 Term 2


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