Today’s problem — free all day, every step. Every day has one.
Ali's stickers — shared with Ben and Carol
Ali gave of his stickers to Ben and of the remainder to Carol. If Ali had 90 stickers at first, how many did Carol receive?
See all 6 steps
MathBrush is being tested with a few parent groups, and every solution on the site is open to them — one household, all children. If you were given a code, it goes in once and this device remembers it.
I have a code → See the free ones
65 worked examples are free without a code, two from every pattern. No account, either way.
The pattern behind it: Branching
The second fraction is of one piece, not of the whole.
In this one. Cut the whole into 6 units so that both fractions land on unit lines: the remainder is then 5 units, and 2/5 of 5 units is exactly 2 units — which is 2/5 × 5/6 = 1/3 of the whole.
How to spot it
A second fraction arrives after the first and is attached to a piece rather than to the whole — 'of the remainder', 'of what was left', or 'of the ones that were red'.
Common mistake
Children take the second fraction of the original total instead of the piece it was named against, which makes the amount come out too big.
Try one like it
Standard Mr Ong's pay — rent then groceries Mr Ong earns $1200 a month. He spent 1/2 of it on rent and 1/3 of the remainder on groceries. How much money did he have left?The 33 problem patterns
All 33 patterns, one to a page — the 19 behind Primary 5 and 6 word problems, and the skills the younger years are built on. The bar model, how to spot it in the question, and the mistake children make. A booklet you can print. Free.
A PDF, and a note when new solutions go up.