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SHORT METHODS.

Multiplication and Division.

Art. 1. To multiply a number by 50: Multiply } of the number by 100. Why?

46 x 50 of 46 x 100 = 2300
47 x 50 of 47 x 100 = 2350

Multiply:
44 by 50 32 by 50 35 by 50
36 by 50 38 by 50 27 by 50
64 by 50 42 by 50 55 by 50
82 by 50 76 by 50 43 By 50

46 by 50 52 by 50 53 by 50 (a) Find the sum of the fifteen products.

Art. 2. To multiply a number by 51: Take 50 times the number, to which add the number itself. Why? 48 x 50 50 times 48

= 2400

2400 + 48 = 2448 37 x 51 50 times 37 = 1850 1850 + 37 = 1887

Multiply:
26 by 51 34 by 51 35 by 51
46 by 51 32 by 51 29 by 51
24 by 51 42 by 51 43 by 51
66 by 51 84 by 51 33 by 51

36 by 51 38 by 51 39 by 51 (b) Find the sum of the fifteen products.

Art. 3. To multiply a number by 52: Take 50 times the number, to which add twice the number. Why? 34 x 52 50 times 34

= 1700 1700 + 68 = 1768 45 x 52 50 times 45 = 2250 2250 + 90 = 2340

Multiply:
26 by 52 38 by 52 27 by 52
18 by 52 14 by 52 17 by 52
24 by 52 32 by 52 35 by 52

36 by 52 44 by 52 23 by 52 (c) Find the sum of the twelve products.

Art. 4. To multiply a number by 49: Take 50 times the number, from which subtract the number itself. Why?

24 x 49 50 times 24 = 1200 1200 24 = 1176 33 x 49 50 times 33 = 1650 1650 33 = 1617

Multiply:
18 by 49 22 by 49 27 by 49
28 by 49 34 by 49 35 by 49

16 by 49 46 by 49 43 by 49 (d) Find the sum of the nine products.

Art. 5. To multiply a number by 33}: Multiply ý of the number by 100. Why? 36 x 33}

of 36 x 100 = 1200
37 x 33 of 37 x 100 = 1233

Multiply:
24 by 33}
27 by 33}

28 by 33
18 by 33 21 by 33;

22 by 33} 30 by 33 33 by 33; 35 by 333 (e) Find the sum of the nine products.

Art. 6. To multiply a number by 343: Take 334 times the number, to which add the number itself. Why? 24 x 343

33į times 24 = 800 800 + 24 = 824 25 x 34 33} times 25 = 833; 833} + 25 = 8583

Multiply:
18 by 34 27 by 34

24 by 34,
21 by 34
33 by 34

39 by 341
30 by 344
36 by 34}

15 by 34
12 by 34
16 by 34

17 by 34} (f) Find the sum of the twelve products.

Art. 7. To multiply a number by 354: Take 33times the number, to which add twice the number. Why? 24 x 35;

333 times 24 = 800 800 + 48 = 848 25 x 35}

33} times 25 = 833} 833} + 50 = 883}

Multiply:
21 by 35}
30 by 35}

27 by 35}
18 by 35 66 by 35;

36 by 35} 33 by 35} 39 by 35

31 by 35} (g) Find the sum of the nine products.

Art. 8. To multiply a number by 324: Take 33f times the number, from which subtract the number itself. Why? 21 x 32}

33} times 21 = 700 700 - 21 = 679 22 x 32

334 times 22 = 733} 733} – 22 = 7114

Multiply:
15 by 32 21 by 32 18 by 32}
24 by 32
30 by 32}

27 by 32}
33 by 32
39 by 32}

36 by 32} (h) Find the sum of the nine products.

=

Art. 9. To multiply a number by 25: Multiply of the number by 100. Why?

48 x 25 1 of 48 x 100 = 1200
49 x 25 À of 49 x 100 - 1225

Multiply:
36 by 25 32 by 25 33 by 25
40 by 25 28 by 25 29 by 25
24 by 25 16 by 25 19 by 25

52 by 25 48 by 25 50 by 25 (i) Find the sum of the twelve products.

Art. 10. To multiply a number by 26:

number by 26: Take 25 times the number, to which add the number itself. Why?

36 x 26 25 times 36 = 900 900 + 36 = 936
37 x 26 25 times 37 = 925 925 + 37 = 963

Multiply:
36 by 26 48 by 26 45 by 26
28 by 26 24 by 26 25 by 26

44 by 26 32 by 26 35 by 26 (j) Find the sum of the nine products.

= 900

Art. 11. To multiply a number by 27: Take 25 times the number, to which add twice the number. Why? 36 x 27 25 times 36

900 + 72 = 972
37 x 27 25 times 37 = 925 925 + 74 = 999

Multiply:
48 by 27 52 by 27 37 by 27
32 by 27 16 by 27 17 by 27

28 by 27 24 by 27 26 by 27 (k) Find the sum of the nine products.

= 768

Art. 12. To multiply a number by 24: Take 25 times the number, from which subtract the number itself. Why?

32 x 24 25 times 32 800 800 32
33 x 24 25 times 33 - 825 825 33 = 792

Multiply:
24 by 24 16 by 24 17 by 24
44 by 24 36 by 24 37 by 24
28 by 24 32 by 24 35 by 24

48 by 24 52 by 24 54 by 24 (1) Find the sum of the twelve products.

Art. 13. To multiply a number by 20: Multiply } of the number by 100. How may a number be multiplied by 21? By 22? By 19 ? 35 x 21 20 times 35 = 700 700 + 35 = 735

Multiply:
45 by 21 45 by 22 45 by 19
35 by 21 35 by 22 35 by 19
36 by 21 36 by 22

36 by 19 (m) Find the sum of the nine products.

Art. 14. To multiply a number by 163: Multiply á of the number by 100. How may a number be multiplied by 17z? By 18z? By 15ş? 24 x 17

163 times 24 = 400 400 + 24

Multiply:
18 by 173 18 by 18 18 by 15;
30 by 17

30 by 18; 30 by 15 36 by 17% 36 by 18 36 by 15 (n) Find the sum of the nine products.

= 424

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