Note to recorder:
First, natural speed. Second time, pretend you are counting something as quickly as possible in your head, please. Thanks!
-10, -9, -8, -7, -6, -5, -4, -3, -2, -1,
0, 1, 2, 3, 4, 5, 6, 7, 8, 9,
10, 11, 12, 13, 14, 15, 16, 17, 18, 19,
20, 21, 22, 23, 24, 25, 26, 27, 28, 29,
30, 31, 32, 33, 34, 35, 36, 37, 38, 39,
40, 41, 42, 43, 44, 45, 46, 47, 48, 49,
50, 51, 52, 53, 54, 55, 56, 57, 58, 59,
60, 61, 62, 63, 64, 65, 66, 67, 68, 69,
70, 71, 72, 73, 74, 75, 76, 77, 78, 79,
80, 81, 82, 83, 84, 85, 86, 87, 88, 89,
90, 91, 92, 93, 94, 95, 96, 97, 98, 99,
100
13, 30
14, 40
15, 50
16, 60
17, 70
18, 80
19, 90
$13 $30
$14 $40
$15 $50
$16 $60
$17 $70
$18 $80
$19 $90
$100
1313 B.C.
1330 B.C.
3013 B.C.
3030 B.C.
-2 - (-3) = 1
-2 + (-3) = -5
2 × 4 + 5 = 13
2 × (4 + 5) = 18
In English, the natural grouping of numbers is:
0,
1,2,3,4,5,6,7,8,9,10
11,12,13,14,15,16,17,18,19,20,
and so on. At least it is for me.