ADDITION AND SUBTRACTION KS2

The key to successful addition and subtraction is a solid understanding of place value and number bonds. Year 3 – fluent in bonds to 10 and 20, and use this to derive other facts over 100. PV to Year 4 – using known bonds to derive other facts, over PV to Year 5/6 - using known bonds to derive other facts, including decimals.

Vocabulary

ADDITION – Mental Strategies  Counting on (by partitioning the second number and counting on; +100, +50)  Partitioning ( =700, 50+60=110, 6+2=8)  Adjusting (by adding 200 and subtracting 1)  Using know number facts = 107 so =6107  Estimating is approximately

ADDITION - Partitioning = ? = ? = 87

ADDITION - Partitioning = ? = ? = ? = 387

ADDITION – Moving towards column method using manipulatives =

ADDITION – Moving towards column method = H T U = 372

ADDITION – Expanded column addition = H T U units 60 tens 300 hundreds 372

ADDITION – Expanded column addition = H T U units tens hundreds00 387

ADDITION – Expanded column addition = H T U

ADDITION – condensed column addition =

ADDITION – Condensed column addition =

ADDITION – Expanded column addition =

SUBTRACTION – Mental strategies  Counting back 564 – 150 (by partitioning the second number and counting back; -100, -50)  Counting up 607 – 288 (by counting up from 288, bridging the hundreds boundary; +12, + 300, +7)  Adjusting 1487 – 199 (by subtracting 200 and adding 1)  Using know number facts =400 so =6400  Estimating is approximately

SUBTRACTION – Number lines  343 – 170 = ?  72 – 36 = ?

SUBTRACTION – Moving towards expanded column method with no decomposition = ? T U

SUBTRACTION – Moving towards expanded column method with decomposition = ? T U T U

SUBTRACTION – Moving towards expanded column method with decomposition.

SUBTRACTION – condensed column method with out decomposition

SUBTRACTION – condensed column method with decomposition