To work out an answer, often by adding or subtracting.

Not wasting time or effort. An efficient strategy is one we can carry out easily.

Explain different strategies used to subtract

Maths

In this unit pupils will learn to find 10 more or less than a 2-digit number. They will  add and subtract 10 to/from a 2-digit number using number facts. In the future unit pupils will add 3 addends, understanding they can be added in any order, bridging through 10.

In the prior unit pupils added and subtracted 1s and 10s from 2 digit numbers. They used number facts to add/subtract a single-digit number to/from a 2-digit number and used a part-part-whole model to represent addition and subtraction. In this unit pupils will learn to find 10 more or less than a 2-digit number. They will  add and subtract 10 to/from a 2-digit number using number facts.

Addition and subtraction of two 2-digit numbers

Izzy wants to solve the equation 38 − 2 = ? Which is the most efficient strategy to use?

Andeep has £65 and he buys a penguin. Which known fact should he use to calculate how much money he has left?

Match each equation to say which digit will change when it is solved. 

Match the equations which will leave the same part remaining.

Fill in the missing number to solve the equation. 65 − 34 = ?

Which equation represents the number line?

Izzy has 38 beads on her bracelet and she adds 55 more. Izzy now has {{ }} beads on her bracelet. Use the strategy you find most efficient to solve the problem.

Which strategy is the most efficient when solving this problem? Izzy sees 62 ants and Andeep sees 21 ants. How many ants do they see altogether?

Which of the following is the most efficient to solve this problem. Andeep’s string is 37 cm long and Izzy’s is 24 cm long. What will they measure when they put them together?

Izzy sees 24 birds and Andeep sees 66     How many more birds does Andeep see? How many ones will be in the missing addend when the equation is written for this problem?

There are 34 red sweets and 51 green sweets. How many more green sweets are there? What is the tens digit in the missing addend?

Izzy’s ladybird crawled 34 cm and Andeep’s ladybird crawled 67 cm. Andeep's ladybird crawled {{ }} cm further than Izzy's.

Starter Quiz