Question paper, Set 4

(i) Start at $7$ and count on $1$: $7 + 1 = 8$

(ii) Count back $4$ from $9$: $9 - 4 = 5$

Answer: (i) $8$ (ii) $5$

$8$ needs $2$ to make $10$; take $2$ from $8$, which leaves $6$.

$8 + 8 = 10 + 6 = 16$

Answer: $\square = 6$; $8 + 8 = 16$

$\square = 8 - 5 = 3$

Check: $5 + 3 = 8$

Answer: $3$

(i) $30 = 20 + 10$ and $10 - 5 = 5$, so $30 - 5 = 20 + 5 = 25$

(ii) $50 = 40 + 10$ and $10 - 9 = 1$, so $50 - 9 = 40 + 1 = 41$

Answer: (i) $25$ (ii) $41$

Take $5$ from the units digit: $9 - 5 = 4$; the tens digit $2$ stays.

$29 - 5 = 24$

Answer: $24$

1st method: take $7$ out of $8$ first ($8 - 7 = 1$): $17 - 8 = 10 - 1 = 9$

2nd method: add $2$ to both: $17 - 8 = 19 - 10 = 9$

Both methods give $17 - 8 = 9$

Answer: $9$

1st method: take $1$ out of $6$ first ($6 - 1 = 5$): $41 - 6 = 40 - 5 = 35$

2nd method: add $4$ to both: $41 - 6 = 45 - 10 = 35$

3rd method: $41 - 10 = 31$ and $10 - 6 = 4$, so $41 - 6 = 31 + 4 = 35$

All three methods give $41 - 6 = 35$

Answer: $35$

Take $1$ ten from $8$ tens: $8 - 1 = 7$; the units digit $2$ stays.

$82 - 10 = 72$

Answer: $72$

1st method (take the tens first): $74 - 47 = 34 - 7 = 30 - 3 = 27$

2nd method: add $3$ to both: $74 - 47 = 77 - 50 = 27$

3rd method: $74 - 50 = 24$ and $50 - 47 = 3$, so $74 - 47 = 24 + 3 = 27$

4th method (column): $4 < 7$, so borrow $1$ ten: units $14 - 7 = 7$, tens $6 - 4 = 2$

All four methods give $74 - 47 = 27$

Answer: $27$

(i) $450 = 440 + 10$ and $10 - 4 = 6$, so $450 - 4 = 440 + 6 = 446$

(ii) units $6 - 2 = 4$, tens $4 - 3 = 1$, hundreds $2$ stays: $246 - 32 = 214$

Answer: (i) $446$ (ii) $214$

1st method (take the tens first): $360 - 35 = 330 - 5 = 325$

2nd method: add $5$ to both: $360 - 35 = 365 - 40 = 325$

3rd method: $360 - 40 = 320$ and $40 - 35 = 5$, so $360 - 35 = 320 + 5 = 325$

4th method (column): $0 < 5$, so borrow $1$ ten: units $10 - 5 = 5$, tens $5 - 3 = 2$, hundreds $3$

All four methods give $360 - 35 = 325$

Answer: $325$

Take away the tens first: $100 - 40 = 60$

$100 - 47 = 60 - 7 = 53$

Answer: $53$

1st method (column): units $5 < 6$, borrow $1$ ten: $15 - 6 = 9$

tens: $8 < 9$, borrow from the hundred: $18 - 9 = 9$, hundreds $0$

2nd method: take $5$ from both: $195 - 96 = 190 - 91$

take $90$ from both: $= 100 - 1 = 99$

3rd method: $195 - 100 = 95$ and $100 - 96 = 4$, so $195 - 96 = 95 + 4 = 99$

All three methods give $195 - 96 = 99$

Answer: $99$

Add the tens: $70 + 30 = 100$; the units digit $3$ stays.

$70 + 33 = 103$

Answer: $103$

Tens: $40 + 70 = 110$

Units: $5 + 4 = 9$

$45 + 74 = 110 + 9 = 119$

Answer: $119$

$44 \div 8$: $8 \times 5 = 40$, $44 - 40 = 4$

Bring down $3$, we have $43$: $8 \times 5 = 40$, $43 - 40 = 3$

Bring down $2$, we have $32$: $8 \times 4 = 32$, $32 - 32 = 0$

Remainder $0$, so $4432 \div 8 = 554$

Answer: $554$

$8 \div 5$: $5 \times 1 = 5$, $8 - 5 = 3$

Bring down $1$, we have $31$: $5 \times 6 = 30$, $31 - 30 = 1$

Bring down $2$, we have $12$: $5 \times 2 = 10$, $12 - 10 = 2$

Bring down $9$, we have $29$: $5 \times 5 = 25$, $29 - 25 = 4$

Bring down $9$, we have $49$: $5 \times 9 = 45$, $49 - 45 = 4$

Bring down $9$, we have $49$: $5 \times 9 = 45$, $49 - 45 = 4$

Bring down $0$, we have $40$: $5 \times 8 = 40$, $40 - 40 = 0$

Remainder $0$, so $8129990 \div 5 = 1625998$

Answer: $1625998$

$12 \div 3$: $3 \times 4 = 12$, $12 - 12 = 0$

Bring down $0$, we have $0$: $0 < 3$, so write $0$ in the quotient

Bring down $8$, we have $8$: $3 \times 2 = 6$, $8 - 6 = 2$

Bring down $7$, we have $27$: $3 \times 9 = 27$, $27 - 27 = 0$

Remainder $0$, so $12087 \div 3 = 4029$

Do not miss the $0$ in the quotient.

Answer: $4029$

$75 \div 11$: $11 \times 6 = 66$, $75 - 66 = 9$

Bring down $6$, we have $96$: $11 \times 8 = 88$, $96 - 88 = 8$

Bring down $8$, we have $88$: $11 \times 8 = 88$, $88 - 88 = 0$

Remainder $0$, so $7568 \div 11 = 688$

Answer: $688$

$\displaystyle \frac{25}{5}$ means $25 \div 5$.

$5 \times 5 = 25$, so $\displaystyle \frac{25}{5} = 5$

Answer: $5$