Basic Facts
L.O : To become more accurate and faster at this set of basic facts: What = 100 (Decades)
Understand - Practise - Learn - Know
Adding to 100 using multiples of 10
Basic Facts
Complete your Basic Facts Test.
Record your score and the time it took you.
Look at your facts to 100.
Do they need work?
Then get to it!
Date | Time | Score |
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Are you becoming more accurate? Are you getting quicker?
3 + 7 = 10
7 + 3 = 10
10 - 7 = 3
10 - 3 = 7
Understand:
You know you number bonds to 10, so these facts will look similar - same numbers with 0s. (same numbers x 10)
becomes
30 + 70 = 100
70 + 30 = 100
100 - 70 = 30
100 - 30 = 70
Learn: Adding to 100 using multiples of 10
0 + 100 = 100
10 + 90 = 100
20 + 80 = 100
30 + 70 = 100
40 + 60 = 100
60 + 40 = 100
70 + 30 = 100
80 + 20 = 100
90 + 10 = 100
You could:
Recite them to yourself
Pop on a screen-castify
Or copy them out on a white board
Or repeat them while bouncing a ball outside.
Or write them out on a Family of Facts △
Laminated sheet.
Or get a set of flashcards and test a friend.
Play the Memory card game with 2 other friends.
Create pairs that add to 100.
You can have them numbers up for first round then turn them numbers down and play Memory with them.
The person with the most pairs wins.
60 40
30
70
10
90
Practise
Practise: How fast can you do these?
addend | addend | sum |
90 | | 100 |
30 | 70 | |
20 | | 100 |
| 60 | |
70 | | 100 |
| 0 | 100 |
10 | | 100 |
Complete this Mad Maths Activity. Take a screenshot of your results and paste your them on the next slide
Post your Mad Maths results ‘screen shot’ here.
Understand: Subtraction to 100 using multiples of 10
0 + 100 = 100
10 + 90 = 100
20 + 80 = 100
30 + 70 = 100
40 + 60 = 100
60 + 40 = 100
70 + 30 = 100
80 + 20 = 100
90 + 10 = 100
100 - 10 = 90
100 - 20 = 80
100 - 30 = 70
100 - 40 = 60
100 - 50 = 50
The opposite of addition of subtraction
If you know one fact, you know and understand 3 others.
20 + 80 = 100 so 100 - 20 = 80
80 + 20 = 100 so 100 - 80 = 20
Practise: How fast can you do these?
10 + . . = 100 | 40 +. . = 100 |
. . + 90 = 100 | . . + 60 = 100 |
100 - . . = 10 | 100 - . . = 40 |
100 - 90 = . . | 100 - 60 =. . |
20 + . . = 100 | 100 + . . =100 |
. . + 80 = 100 | . . + 0 = 100 |
100 - . . = 20 | 100 - . . = 100 |
Watch the sign!
Is it + OR - ?