Grade 3 · Unit 1: Number and place value

Adding in your head

Split, jump and adjust.

Mental maths at the market

A seller adds ৳45 and ৳38 in a second. They use strategies. Let us learn some.

Partition

Partition both numbers into tens and ones. Add tens: 40 + 30 = 70. Add ones: 5 + 8 = 13. 70 + 13 = 83.

Jump on a number line

Keep the first number whole. Jump the tens, then the ones. 146 + 30 = 176, 176 + 7 = 183.

Round and adjust

99 is a near multiple of 100. Add 100 instead, then take away the extra 1. This is called compensating.

What I learnt

• I can partition to add.
• I can use a number line.
• I can round and adjust.