November, 2012
Mousumi Ofset Press, 38 Banglabazar, Dhaka.
Elementary Mathematics
We multiply 32 4 128
3 tens 2
39 7 273
4 12 tens 8 1 hundred 2 tens 8
3 tens 9 7 21 tens 63 27 tens 3 2 hundreds 7 tens 3 273
128
45 14 180 450
45 14
4 tens 5 1 tens 4
18 tens
630
132 3 396
4 tens 5 4 16 tens 20 180
1 hundred 3 tens 2
3 3 hundreds 9 tens 6
148 4 592
396
4 tens 5 1 tens 4 hundreds 5 tens 450 4 tens 5 4 4 tens 5 1 tens
180 450 630
1 hundred 4 tens 8 4 4 hundreds 16 tens 32 4 hundreds 19 tens 2 5 hundreds 9 tens 2 592
With the help of multiplication table 256 2 hundreds 5 tens 6 18 6 108 90 tens 18 18 5 tens 18 18 2 hundreds 36 hundreds 4608
49
108 900 3600 4608
Elementary Mathematics
We multiply
243 35 1215
2 hundreds 4 tens 3
2 hundreds 4 tens 3
3 tens 5
2 hundreds 4 tens 3 30 (3 tens = 30)
5
10 hundreds 20 tens 15 6 thousands 12 hundreds 90
7290
10 hundreds 21 tens 5
8505
12 hundreds 1 tens 5
7 thousands 2 hundreds 90
7290
1215 2 hundreds 4 tens 3 5 2 hundreds 4 tens 3 30
1215 7290 8505
204 6 1224
348
410
507
7
8
9
325
370
278
218
15
24
28
37
267
189
223
103
23
45
38
56
50
Elementary Mathematics
Problems related to multiplication Example 1. Solution :
1 hali is equal to 4 . How many will be in 16 hali ? 1 hali = 4 items 16 hali = 4 × 16 items = 64 items 16 hali will be 64 items.
Example 2. Solution :
1 dozen is equal to 12. How many will be in 12 dozens ? 1 dozen = 12 items 12 dozen = 12 × 12 items = 144 items 12 dozens will be 144 items.
Example 3. Solution :
The price of 1 kg mango is Tk. 65. What will be the price of 8 kg mangoes ? Price of 1 kg mango = Tk. 65 65 8 Price of 8 kg mangoes = Tk. (65 × 8) 520 = Tk. 520 The price of 8 kg mangoes will be Tk. 520.
Example 4. The price of a hilsha fish is Tk. 375. What will be the price of 16 hilsha fishes? Solution : Price of 1 hilsha fish = Tk. 375 Price of 16 hilsha fishes = Tk. (375 × 16) = Tk. 6000 The price of 16 hilsha fishes will be Tk. 6000. 51
375 16 2250 3750 6000
Elementary Mathematics
Let us do ourselves 1. We colour the correct number (a) 8 9
64, 72, 80, 90
(c) 13 3 (e) 16 8
26, 30, 39, 52 102, 128, 144, 160
2. We fill up the blank spaces (a) 10 10 (c)
50, 55, 60, 72
(d) 14 6 (f) 17 4
28, 42, 56, 84
(b) 15 (d)
18 8 multiplicant
19
68, 85, 102, 119
9 6
multiplier multiplicant
product
product
multiplier
3. We multiply (a) 22 8 (e) 105 6 (i) 478 5
(b) 12 5
(b) 64 8 (f) 178 8 (j) 637 8
4. We multiply in short (b) 30 (a) 25 10 (f) 165 (e) 125 50
(c) 48 9 (g) 240 7 (k) 809 8
20 60
(c) 40
40
(d) 85 8 (h) 305 7 (l) 909 9 (d) 80
30
5. We find the product (a)
330 9
(e)
97 48
(b) 4 6 5 8
(c)
55 25
(d)
88 30
(f)
(g)
207 35
(h)
276 28
178 25
52
Elementary Mathematics
6. I pair is equal to 2 items. How many will be in 8 pairs ? 7. 1 hali is equal to 4 items. How many will be in 5 hali? 8. If in a bundle there are 6 flowers, then how many flowers will be in 8 bundles ? 9. Toma reads 4 hours daily. How many hours does she read in a week? 10. There are 24 sheets of paper in a quire. How many sheets will be in 12 quire? 11. There are 15 rows of betel-nut trees in Ranu’s garden and in each row there are 24 trees. How many trees are in the garden? 12. Tondra Chakma drives at the rate of 45 kilometres per hour. How many kilometres will she go in 8 hours at the same speed? 13. 1 taka is equal to 100 paisas. How many paisas will be in Tk. 10? 14. There are 130 pages in a book. How many pages are there in 28 such books? 15. Nipu has 14 times of what Rimi has. If Rimi has Tk. 225 then how many taka does Nipu have ? 16. The price of a hilsha fish is Tk. 350. What is the price of 20 such hilsha fishes?
53
Elementary Mathematics
Division Concept of division
8
2
2
2
2 8
4
2
9
3
3 9
3
3
3
9 6 3
3
3
3
6
3
0
From 9 tops, 3 tops may be taken 3 times leaving no top behind. Therefore, 9 can be divided by 3 thoroughly.
Division is repeated subtraction 54
Elementary Mathematics
42
6
what ?
6
what ?
6
7
42
Therefore, 42
30
5
48
6
81
9
6 42 7 42 0
42
6
9 72 8 72 0
8 72 9 72 0
7
7 56
6 54
Dividend, Divisor, Quotient and Remainder
40
5
Dividend
8
Divisor
Divident Divisor
Quotient
Dividend
40
5
5
40
Divisor
Quotient
Dividend
Quotient
Divisor
Quotient
8 8
Thorough division is reverse method of multiplication 55
Elementary Mathematics
From 22 mangoes taking 5 at a time 22 mangoes may be taken 4 times and remain 2 22
5
4
2
Dividend Divisor
5 22 4 20 2
Quotient Remainder
Dividend = Divisor Ă— Quotient + Remainder 9 63 7 63 0 Here, Divisor Dividend Quotient
* * * * * *
8 75 9 72 3 Here, Divisor Dividend Quotient Remainder
The number by which division is done is the divisor. The number which is divided is the dividend. The number obtained after the division is the quotient. The number which remains after the division is the remainder. Remainder must be smaller than the divisor. If the remainder is zero, then the dividend is thoroughly divisible by the divisor. 56
"For free distribution by the Government of Bangladesh- Not for sale"
"For free distribution by the Government of Bangladesh- Not for sale"