Near Doubles
I am learning to solve addition problems where the two
numbers are easily related to doubles.
e.g. 9 + 9 = 18
Or
80 + 80 = 160
Craig has $79 and saves another $81. How much money does he
have? 79 + 81 = ?
Step 1: Let’s use some notes and coins to represent this question.
Step 2: If we move $1 from the $79 to the $80 then both piles will
have $80.
Step 3: Swap the ten $1 coins for a $10 note and then both groups
have $80
80 + 80 = 160
$10
$10
$10
$10
$10
$10
$10
$10
1
1
1
1
1
1
1
1
1
1
$10
$10
$10
$10
$10
$10
$10
$10
1
Kim drove 78km on Monday and 79km on Tuesday. How many
kilometres has she driven?
78 + 79 = ?
78 + 79 = ……
+2
+1
Step 1: Let’s use our doubles to help us
answer this question. Change the
question into 80 + 80. This will be much
easier to answer.
80 + 80 = 160
Step 2: We added 2 to the 78 and 1 to the 79 (a total of 3). So now
we must subtract 3 from our answer of 160.
160 – 3 = 157
Now try these questions on your own.
1) 69 + 71 = ?
140
2) 38 + 38 = ?
76
3) 89 + 92 = ?
181
4) 148 + 252 = ?
400
5) 119 + 119 = ?
238
Click again when you have
completed each question and
the answer will be displayed.
Need some more practise? Try Pg55 of Teacher Tools Addition and
Subtraction Book Numeracy resources