Mental Math · Subtraction · S1
Subtraction works just like addition in your head: split the number you are taking away into its place-value parts, and remove them one chunk at a time — biggest first.
Watch the method
Don't take away 34 all at once. Take away the 30 first (92 − 30 = 62), then the 4 (62 − 4 = 58). Two easy steps.
Take away the tens.
Take away the ones.
Your turn
Use the method, then check. Stuck? Reveal the steps.
Taking away 30 lands you on a clean number (62), and taking away the last 4 is then trivial. Same logic as adding the big parts first — just in reverse.
Why it works
Like paying a bill: hand over the tens first, then the loose coins.
76 − 23
Tens
76 − 20 = 56.
Ones
56 − 3 = 53.
92 − 34
Tens
92 − 30 = 62.
Ones
62 − 4 = 58.
826 − 349
Hundreds
826 − 300 = 526.
Tens
526 − 40 = 486.
Ones
486 − 9 = 477.
Subtracting the ones first and getting tangled.
Take the tens away first. It leaves a tidy number, so the ones step stays simple.
Forgetting a borrow when the ones don't 'fit'.
You never borrow here. 62 − 4 just counts back 4 to 58 — no columns, no borrowing.
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).92 − 34 = ?
76 − 23 = ?
85 − 41 = ?
68 − 25 = ?
145 − 32 = ?
263 − 41 = ?
154 − 63 = ?
247 − 35 = ?
532 − 218 = ?
645 − 327 = ?
473 − 258 = ?
826 − 349 = ?