Mental Math · Decimals · Subtract
Subtracting decimals is subtracting in parts. Take away the whole-number part first to land on a tidy number, then take away the decimal part. The point just keeps the columns lined up.
Watch the method
6.2 − 2.8: take away the 2 (6.2 − 2 = 4.2), then take away the 0.8 (4.2 − 0.8 = 3.4).
Subtract the whole-number part.
Subtract the decimal part.
Your turn
Use the method, then check. Stuck? Reveal the steps.
Removing the whole number lands you on an easy decimal; removing the decimal part is then a small step. Same 'subtract in parts' method, with the point along for the ride.
Why it works
6.2 − 2.8: pay the 2 dollars first, then the 80 cents.
7.5 − 1.3
Whole
7.5 − 1 = 6.5.
Decimal
6.5 − 0.3 = 6.2.
6.2 − 2.8
Whole
6.2 − 2 = 4.2.
Decimal
4.2 − 0.8 = 3.4.
12.3 − 4.8
Whole
12.3 − 4 = 8.3.
Decimal
8.3 − 0.8 = 7.5.
Dropping the point and doing 62 − 28.
Keep place value: 6.2 − 2.8 = 3.4, not 34.
Lining up the last digits instead of the points.
Always line up the decimal points. 6.2 − 0.45 means tenths under tenths, not 2 under 5.
12 problems across three tiers. Auto-graded on submit. Hints and a full walkthrough on every question. Your work is saved on this device — sign in to keep it across devices.
t₁ = 5, d = 3 and t1=5,d=3 both count. For a list of numbers, separate them with commas (e.g. 3, 10, 17).6.2 − 2.8 = ?
7.5 − 1.3 = ?
9.1 − 4.6 = ?
5.4 − 2.7 = ?
12.3 − 4.8 = ?
10 − 3.6 = ?
8.6 − 5.9 = ?
15.2 − 6.7 = ?
23.4 − 15.8 = ?
10.5 − 0.7 = ?
31.2 − 18.6 = ?
7.3 − 4.5 = ?