MathBrush

The pattern

Large numbers and operation order

Group digits by place value, then do brackets and multiplication or division before addition or subtraction.

Large numbers and operation order illustrated in pencil.
Order changes the resultno bracketsmultiply before adding: 90bracketsbrackets first: 378

Large numbers add up correctly only when digits of the same place value sit under each other: ones under ones, tens under tens, hundreds under hundreds. Line the numbers up this way before adding, and carry any digit that makes a column reach ten into the column on its left. Ordering numbers compares the hundreds digit first, moving to tens only if the hundreds match.

How to spot it

Two numbers to add with carrying, several numbers to put in order, or a sum mixing addition, multiplication and brackets, all point here.

Common mistake

Children forget to carry a ten into the next column, or compare digits from the left without first checking the numbers have the same number of digits.

104 worked solutions

Standard

All the problem patterns → · the revision list

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.