Perkalian dengan 3 : Menghitung Cepat

1 x 3 = 3 = 1 + 2 = 1 + 1.2
2 x 3 = 6 = 2 + 4 = 2 + 2.2
3 x 3 = 9 = 3 + 6 = 3 + 3.2

4 x 3 = 12 = 4 + 8 0= 4 + 4.2
5 x 3 = 15 = 5 + 10 = 5 + 5.2
6 x 3 = 18 = 6 + 12 = 6 + 6.2
7 x 3 = 21 = 7 + 14 = 7 + 7.2
8 x 3 = 24 = 8 + 16 = 8 + 8.2
9 x 3 = 27 = 9 + 18 = 9 + 9.2

Rumus Umum :

1. XYZ x 3 = XYZ + XYZ + XYZ
2. XYZ x 3 = 3.X3.Y3.Z

Perkalian dengan 2 : Menghitung Cepat

1 x 2 = 2 = 1 + 1
2 x 2 = 4 = 2 + 2
3 x 2 = 6 = 3 + 3
4 x 2 = 8 = 4 + 4

5 x 2 = 10 = 5 + 5
6 x 2 = 12 = 6 + 6 = (5 + 1) + (5 + 1) = 5 + 5 + 1 + 1 = 10 + 1 + 1 = 10 + 2 = 1|2 = 12
7 x 2 = 14 = 7 + 7 = (5 + 2) + (5 + 2) = 5 + 5 + 2 + 2 = 10 + 2 + 2 = 10 + 4 = 1|4 = 14
8 x 2 = 16 = 8 + 8 = (5 + 3) + (5 + 3) = 5 + 5 + 3 + 3 = 10 + 3 + 3 = 10 + 6 = 1|6 = 16
9 x 2 = 18 = 9 + 9 = (5 + 4) + (5 + 4) = 5 + 5 + 4 + 4 = 10 + 4 + 4 = 10 + 8 = 1|8 = 18

Rumus Umum :

1. XYZ x 2 = XYZ + XYZ
2. XYZ x 2 = X + X|Y + Y|Z + Z

Perkalian dengan 1 : Menghitung Cepat

1 x 1
2 x 1
3 x 1
4 x 1
5 x 1
6 x 1
7 x 1
8 x 1
9 x 1

Rumus umum : Bilangan yang dikali dengan 1 hasilnya bilangan itu sendiri.

Perkalian dengan 111 : Menghitung Cepat

Ada beberapa cara :

1. abc x 111 = abc.(100 + 11) = abc00 +
000a|a+b|b+c|c
2. abc x 111 = abc.(110 + 1) = a|a+b|b+c|c0 + abc
3. abc x 111 = a|a.1+b.1|a.1+b.1+c.1|b.1+c.1|c
4.

1 x 111 = 111 = 1|1|1
2 x 111 = 222 = 2|2|2
5 x 111 = 555 = 5|5|5

10 x 111 = 1110 = 1|1+0|1+0|0
13 x 111 = 1443 = 1|1+3|1+3|3

20 x 111 = 2220 = 2|2+0|2+0|0
24 x 111 = 2664 = 2|2+4|2+4|4

100 x 111 = 11100 = 1|1+0|1+0+0|0+0|0
106 x 111 = 11766 = 1|1+0|1+0+6|0+6|6
111 x 111 = 12321 = 1|1+1|1+1+1|1+1|1

Rumus Umum :

abc x 111 = a|a+b|a+b+c|b+c|c

Perkalian dengan 99 : Menghitung Cepat

Ada beberapa cara :

1. XY x 99 = XY.(100 - 1) = XY00 - XY
2. XY x 99 = 9.X|9.X + 9.Y|9.Y = 9.X|9.(X + Y)|9.Y
3. (XY x 9).11 = (9.X|9.Y).11 = 9.X|9.(X + Y)|9.Y
4.

1 x 99 = 99 = (01 - 1)(9 - 0) | (10 - 1)
2 x 99 = 198 = (02 - 1)(9 - 0) | (10 - 2)
5 x 99 = 495 = (05 - 1)(9 - 0) | (10 - 5)

10 x 99 = 990 = (10 - 1)(9 - 1) | (10 - 0)
11 x 99 = 1089 = (11 - 1)(9 - 1) | (10 - 1)
13 x 99 = 1287 = (13 - 1)(9 - 1) | (10 - 3)

24 x 99 = 2376 = (24 - 1)(9 - 2) | (10 - 4)

90 x 99 = 8910 = (90 - 1)(9 - 9) | (10 - 0)

111 x 99 = 10989 = (111 - 1)(9 - 11)(10 - 1)

Rumus Umum :

XY x 99 = [XY - 1] [9 - X] | [10 - Y]

XYZ x 99 = [XYZ - 1] [9 - XY] | [10 - Z]

Perkalian dengan 25 : Menghitung Cepat

Rumus Umum :

A x 25 = A x (100/4) = (A/4) x 100

Contoh :

1 x 25 = (1/4) x 100 = 0,25 x 100 = 25

2 x 25 = (2/4) x 100 = 0,50 x 100 = 50

3 x 25 = (3/4) x 100 = 0,75 x 100 = 75

4 x 25 = (4/4) x 100 = 1+(0/4) x 100 = 100

7 x 25 = (7/4) x 100 = 1+(3/4) x 100 = 175

14 x 25 = (14/4) x 100 = 3+(2/4) x 100 = 350

Perkalian dengan 9 (1) : Menghitung Cepat

1 x 9 = (1 - 1)9 = 09

2 x 9 = (2 - 1)8 = 18

11 x 9 = (11 - 2)9 = 99

13 x 9 = (13 - 2)7 = 117

21 x 9 = (21 - 3)9 = 189

24 x 9 = (24 - 3)6 = 216

91 x 9 = (91 - 10)9 = 819

95 x 9 = (95 - 10)5 = 855

101 x 9 = (101 - 11)9 = 909

106 x 9 = (106 - 11)4 = 954

111 x 9 = (111 - 12)9 = 999

117 x 9 = (117 - 12)3 = 1053

121 x 9 = (121 - 13)9 = 1089

191 X 9 = (191 - 20)9 = 1719

201 X 9 = (201 - 21)9 = 1809

900 X 9 = (900 - 91)|10 = 809|10 = 8100

901 X 9 = (901 - 91)9 = 8109

Rumus Umum :

XY x 9 = [XY - (X + 1)]|(10 - Y)

XYZ x 9 = [XYZ - (XY + 1)]|(10 - Z)