SHORT METHODS IN MULTIPLICATION AND DIVISION. Art. 1. To multiply a number by 50: Multiply of the number by 100. Why? (b) Find the sum of the twelve products. Art. 3. To multiply a number by 52: number, to which add twice the number. Take 50 times the Why? = 1700+ 68 1768 27 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? (d) Find the sum of the twelve products. Art. 5. To multiply a number by 33: Multiply of the (e) Find the sum of the twelve products. Art. 6. To multiply a number by 341: the number, to which add the number itself. Take 33 times (f) Find the sum of the twelve products. Art. 7. To multiply a number by 35: the number, to which add twice the number. Take 33 times 800 +48 848 = 24 × 351 33 times 25 = 8331 (g) Find the sum of the twelve products. Art. 8. To multiply a number by 321: Take 33 times the number, from which subtract the number itself. Why? (h) Find the sum of the twelve products. Art. 9. To multiply a number by 25: Multiply of the number by 100. Why? (i) Find the sum of the twelve products. Art. 10. To multiply a number by 26: Take 25 times the number, to which add the number itself. Why? (j) Find the sum of the twelve products. Art. 11. To multiply a number by 27: number, to which add twice the number. Take 25 times the Why? 900+72=972 36 × 27 25 times 36 = 900 (k) Find the sum of the twelve products. Art. 12. To multiply a number by 24: Take 25 times the number, from which subtract the number itself. Why? (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? (m) Find the sum of the twelve products. Art. 14. To multiply a number by 163: Multiply of the number by 100. How may a number be multiplied by 17? by 18? by 15? (n) Find the sum of the twelve products. |