Number bonds to 100
for 2nd grade
Identify pairs of numbers that sum to a total of 100
Addition - Number bonding - Number bonds to 100
Number bonding is a method for recognizing common combinations of numbers that add to a specific target number. In this topic we are looking at pairs of numbers that bond to 100. So, an obvious pair you might think of is:
50 + 50 = 100
Obviously there are many other multiples of 10 that also bond to 100:
40 + 60 = 100
80 + 20 = 100
10 + 90 = 100
One thing you will notice with the multiples of 10 is that we could knock off the final zero and think about number pairs that bond to 10. You will also notice that we can play around with these bonds to derive related facts - for instance:
30 + 70 = 100
100 = 70 + 30
100 - 70 = 30
100 - 30 = 70
Now, let's think about numbers which aern't multiples of 10 like 34 or 59. One way to quickly get their number bond pair to 100 is to work the units first and then figure out the tens. So, for 34, take the unit 4, bond it to 10 with a unit 6. This pushes the tens 3 to a tens 4. Now figure the tens bond of 4 to make 100 which is 6. So the answer is 66.
34 + ▢ = 100
30 + 4 + ▢ + 6 = 100
30 + 4 + 60 + 6 = 100
So, ... 34 + 66 = 100
Consider another example, say 22:
22 + ▢ = 100
20 + 2 + ▢ + 8 = 100
20 + 2 + 70 + 8 = 100
So, ... 22 + 78 = 100
So knowing your number bonds, or knowing how to quickly work out number bonds can massively speed up your mental arithmetic.
Below is a table showing the first 8 question answer pairs for the topic "Number bonds to 100" as used in the lessons for this topic. Our games and tests for the topic use these 8 items plus 14 additional question answer pairs.
The topic "Number bonds to 100" is in the category Addition for 2nd grade (ages 7 to 8).
Revise 'Number bonds to 100' with one of our games for 2nd grade
Each of our math topics for elementary are made up of between 6 and 20 question and answer pairs (both the written form and a robot voice speaking those questions and answers). Each topic can be used with all the activities on the site.
Counting * Comparing numbers * Pattern * Place value * Addition * Subtraction * Add + Subtract * Multiplication * Division * Multiply + Divide * Fractions * Measurements * Shapes * Position + Direction * Statistics * Algebra *
