Arithmetic

There are six arithmetic expressions and the number system:

• Number system
• Addition
• Subtraction
• Multiplication
• Division
• Roots
• Exponents

Digits

Numbers are made of digits. Here are their names:

0 - zero
1 - one
2 - two
3 - three
4 - four
5 - five
6 - six
7 - seven
8 - eight
9 - nine

Addition

An addition question can look like this:

  3
+ 4
----

or this:

3 + 4 = ____

(the answer is "seven", written as "7")

Worked out this is true because 3 = (equals) 1+1+1 and 4 = (equals) 1+1+1+1. Saying this it would sound like, "Three equals: one, plus one, plus one; and four equals: one, plus one, plus one, plus one."

So 3 + 4 = 1 + 1 + 1 + 1 + 1 + 1 + 1, and all of this (1 + 1 + 1 + 1 + 1 + 1 + 1) equals 7. So 3 + 4 = 7.

Multiplication table

   1   2   3   4   5   6   7   8   9  10  11  12
1  1   2   3   4   5   6   7   8   9  10  11  12
2  2   4   6   8  10  12  14  16  18  20  22  24
3  3   6   9  12  15  18  21  24  27  30  33  36
4  4   8  12  16  20  24  28  32  36  40  44  48
5  5  10  15  20  25  30  35  40  45  50  55  60
6  6  12  18  24  30  36  42  48  54  60  66  72
7  7  14  21  28  35  42  49  56  63  70  77  84
8  8  16  24  32  40  48  56  64  72  80  88  96
9  9  18  27  36  45  54  63  72  81  90  99 108

Division

	1	2	3	4	5	6	7	8	9	10	11	12
1	1	2	3	4	5	6	7	8	9	10	11	12
2	2	4	6	8	10	12	14	16	18	20	22	24
3	3	6	9	12	15	18	21	24	27	30	33	36
4	4	8	12	16	20	24	28	32	36	40	44	48
5	5	10	15	20	25	30	35	40	45	50	55	60
6	6	12	18	24	30	36	42	48	54	60	66	72
7	7	14	21	28	35	42	49	56	63	70	77	84
8	8	16	24	32	40	48	56	64	72	80	88	96
9	9	18	27	36	45	54	63	72	81	90	99	108
10	10	20	30	40	50	60	70	80	90	100	110	120
11	11	22	33	44	55	66	77	88	99	110	121	132
12	12	24	36	48	60	72	84	96	108	120	132	144
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