Helping children understand how to add or subtract near multiples of 10.

Instructions.
Take an A4 piece of card (160g is fine) cut it in half length ways. (This will enable you to create two demo cards with one A4 sheet). Divide each piece of card into four columns and fold one column each side as shown in the diagram opposite.

In the Tens and Units (1’s) column write some numbers as in the diagram. Now cut the flaps so that each numeral can be hidden by a flap.

Next, fold the flaps over to cover up the numbers you have just written and write the new number on the flaps. In the diagram the first number is 12 so write 2 on the tens flap and 3 on the Units flap.

This card demo can now be used for adding 11 and subtracting 11. To add 11, add 1 ten to the tens column and a 1 to the units column. To subtract 11, subtract 1 ten from the tens column and subtract 1 unit from the units column.

Card demo for adding 9

A method that can help.
Below you will find a method that you can demonstrate to your children which shows how to mentally calculate near multiples of ten. The example includes adding near multiples of 10 and subtracting near multiples of 10. Once created you can laminate the card for future use and create a stock of cards so children can add their own numbers. Children who write their own numbers on the card will remember and understand how to add or subtract near multiples of 10 more clearly than those children who just watch your demonstration.

Card demo for adding 11

Card demo for subtracting 11

Card demo for subtracting 9