Grade 4 · Unit 1: Number and place value

Mental addition

Add big numbers in your head.

Cricket totals

In a one-day match, Team A scores 287 and Team B scores 256. What is the total of both innings? You can do this mentally.

Partitioning

Split both numbers into places. Add each place. Combine the totals: 543.

Bridging through 1000

Jump to the next thousand first. 6850 + 150 = 7000. 375 − 150 = 225 more. 7000 + 225 = 7225.

Compensation

2998 is very close to 3000. Add 3000, then take off the 2 extra. Choose the strategy that fits the numbers.

Group to calculate

Look for numbers that make tens: 53 + 17 = 70. 28 + 12 = 40. Grouping makes long additions quick.

What I learnt

• I can partition, bridge and compensate to add mentally.
• I can choose an efficient strategy.