MathKeys.org


Numeracy
10 Digits Make all Numbers: 0, 1, 2, 3, 4, 5, 6, 7, 8, 9
Decimal System: Ten is a two-digit number, 10. The decimal system is based on 10 in a digit parking place system where each spot is a multiple of 10, with the decimal POINT separating whole numbers on the left from fractions of wholes on the right.


Each digit represents an amount. Digits are less than 10.
Zero 0 represents nothing.
Addition, Plus, + Combine
0 = nothing
1 = 0 + 1
1 = 1 + 0
2 = 0 + 2
2 = 1 + 1
2 = 2 + 0
3 = 0 + 3
3 = 1 + 1 + 1
3 = 1 + 2
3 = 2 + 1
3 = 3 + 0
4 = 0 + 4
4 = 1 + 1 + 1 + 1
4 = 1 + 3
4 = 2 + 2
4 = 3 + 1
4 = 4 + 0
5 = 0 + 5
5 = 1 + 1 + 1 + 1 + 1
5 = 1 + 4
5 = 2 + 3
5 = 3 + 2
5 = 4 + 1
5 = 5 + 0
6 = 0 + 6
6 = 1 + 1 + 1 +
1 + 1 + 1
6 = 1 + 5
6 = 2 + 4
6 = 3 + 3
6 = 4 + 2
6 = 5 + 1
6 = 6 + 0
7 = 0 + 7
7 = 1 + 1 + 1
+ 1 + 1 + 1 + 1
7 = 1 + 6
7 = 2 + 5
7 = 3 + 4
7 = 4 + 3
7 = 5 + 2
7 = 6 + 1
7 = 7 + 0
8 = 0 + 8
8 = 1 + 1 + 1 + 1 +
1 + 1 + 1 + 1 +
8 = 1 + 7
8 = 2 + 6
8 = 3 + 5
8 = 4 + 4
8 = 5 + 3
8 = 6 + 2
8 = 7 + 1
8 = 8 + 0
9 = 0 + 9
9 = 1 + 1 + 1
1 + 1 + 1
1 + 1 + 1
9 = 1 + 8
9 = 2 + 7
9 = 3 + 6
9 = 4 + 5
9 = 5 + 4
9 = 6 + 3
9 = 7 + 2
9 = 8 + 1
9 = 9 + 0
MAKING TEN
10 = 0 + 10
10 = 1 + 9
10 = 2 + 8
10 = 3 + 7
10 = 4 + 6
10 = 5 + 5
10 = 6 + 4
10 = 7 + 3
10 = 8 + 2
10 = 9 + 1
10 = 10 + 0
TEENS NUMBERS
TEN + A DIGIT
10 = 10 + 0
11 = 10 + 1
12 = 10 + 2
13 = 10 + 3
14 = 10 + 4
15 = 10 + 5
16 = 10 + 6
17 = 10 + 7
18 = 10 + 8
19 = 10 + 9
Ten 10
Eleven
one + ten = 11
Twelve
two + ten = 12
Thirteen
three + ten = 13


Subtraction, Take Away, Remove
0 = nothing
1 - 0 = 1
1 - 1 = 0
2 - 0 = 2
2 - 1 = 1
2 - 2 = 0
3 - 0 = 3
3 - 1 - 1 - 1 = 0
3 - 1 = 2
3 - 2 = 1
3 - 3 = 0
4 - 0 = 4
4 - 1 - 1 - 1 - 1 = 0
4 - 1 = 3
4 - 2 = 2
4 - 3 = 1
4 - 4 = 0
5 - 0 = 5
5 - 1 - 1 - 1- 1-1 = 0
5 - 1 = 4
5 - 2 = 3
5 - 3 = 2
5 - 4 = 1
5 - 5 = 0
6 - 0 = 6
6 - 1 - 1 - 1 -
1 - 1 - 1 = 0
6 - 1 = 5
6 - 2 = 4
6 - 3 = 3
6 - 4 = 2
6 - 5 = 1
6 - 6 = 0
7 - 0 = 7
7 - 1 - 1 - 1
- 1 - 1 - 1 - 1 = 0
7 - 1 = 6
7 - 2 = 5
7 - 3 = 4
7 - 4 = 3
7 - 5 = 2
7 - 6 = 1
7 - 7 = 0
8 - 0 + 8
8 - 1 - 1 - 1 - 1 -
1 - 1 - 1 - 1 = 0
8 - 1 = 7
8 - 2 = 6
8 - 3 = 5
8 - 4 = 4
8 - 5 = 3
8 - 6 = 2
8 - 7 = 1
8 - 8 = 0
9 - 0 = 9
9 - 1 - 1 - 1
1 - 1 - 1
1 - 1 - 1 = 0
9 - 1 = 8
9 - 2 = 7
9 - 3 = 6
9 - 4 = 5
9 - 5 = 4
9 - 6 = 3
9 - 7 = 2
9 - 8 = 1
9 - 9 = 0
MAKING TEN
10 - 0 = 10
10 - 1 = 9
10 - 2 = 8
10 - 3 = 7
10 - 4 = 6
10 - 5 = 5
10 - 6 = 4
10 - 7 = 3
10 - 8 = 2
10 - 9 = 1
10 - 10 = 0
10 - 0 = 10
11 - 1 = 10
12 - 2 = 10
13 - 3 = 10
14 - 4 = 10
15 - 5 = 10
16 - 6 = 10
17 - 7 = 10
18 - 8 = 10
19 - 9 = 10
20 - 10 = 10
9 + 1 = 10
9 + 2 = 10 + 2 - 1
9 + 3 = 10 + 3 - 1
9 + 4 = 10 + 4 - 1
9 + 5 = 10 + 5 - 1
9 + 6 = 10 + 6 - 1
9 + 7 = 10 + 7 - 1
9 + 8 = 10 + 8 - 1
9 + 9 = 10 + 9 - 1
9 + 10 = 19
9 + 11 = 10 + 9 + 1 = 20
Double Numbers
0 + 0 = 0
1 + 1 = 2
2 + 2 = 4
3 + 3 = 6
4 + 4 = 8
5 + 5 = 10
6 + 6 = 12
7 + 7 = 14
8 + 8 = 16
9 + 9 = 18
10 + 10 = 20
11 + 11 = 22
12 + 12 = 24
Multiplication (Adding the same thing multiple times) & Division (Subtracting the same thing multiple times).


Practice facts many ways:
Add - Subtract:
4 + 5 = 9
4x + 5x = 9x
4xy + 5xy = 9xy
4xyz + 5xyz = 9xyz
40 + 50 = 90
400 + 500 = 900
4,000 + 5,000 = 9,000
4/10 + 5/10 = 9/10
.4 + .5 = .9
4 million + 5 million = 9 M
9 - 5 = 4
.9 - .4 = .5
9/10 - 5/10 = 4/10
9M - 4M = 5M
9¢ - 5¢ = 4¢
$9 - $4 = $5
9/1000 - 5/1000 = 4/1000
9/k - 4/k = 5/k
-5 - 4 = -5
Multiply - Divide:
7 × 9 = 63
9 × 7 = 63
.9 × .7 = .63
63 ÷ 7 = 9
63 ÷ 9 = 7
63x ÷ 7x = 9x
63x ÷ 9x = 7x
63/7 = 9
63/9 = 7
63/10 ÷ 9/10 = 7/10
63/10 ÷ 7/10 = 9/10
63,000 ÷ 9,000 = 7,000
63,000 ÷ 7,000 = 9,000
630 ÷ 90 = 70
630 ÷ 70 = 90
6,300 ÷ 900 = 700
6,300 ÷ 700 = 900
63M ÷ 9M = 7M
63GB ÷ 9GB = 7GB
Multiply - Divide Practice
Example:
3 + 3 + 3 + 3 = 12
3 × 4 = 12
4 × 3 = 12
3(4)= 12
4(3)= 12
3*4 = 12
4*3 = 12
4 • 3 = 12
3 • 4 = 12
Example:
3a + 3a + 3a + 3a = 12a
3a × 4 = 12a
4a × 3 = 12a
3(4a)= 12a
4a(3)= 12a
3a*4 = 12a
4*3a = 12a
4a • 3 = 12a
3a • 4 = 12a
Example:
3/10 + 3/10 + 3/10 + 3/10 = 12/10
3/10 × 4 = 12/10
4/10 × 3 = 12/10
3/10(4)= 12/10
4/10(3)= 12/10
3/10*4 = 12/10
4*3/10 = 12/20
.4 • .3 = .12
.3 • .4 = .12
Multiplication: Short vs. Long
Multiply two digits from R to L, and add the leftovers, then write the product below the line in the column of the multiplicand.
Multiply two digits from R to L and write the product so it ends in the parking spot of the multiplicand. Sum each column.
Long Division


Divide the dividend by the divisor, from L to R. Write the quotient on top in the same column as the digit in the dividend.
Minus - Give Ten, Make 10

