Question paper, Set 5

(i) Start at $8$ and count on $2$: $8 + 2 = 10$

(ii) Count back $1$ from $7$: $7 - 1 = 6$

Answer: (i) $10$ (ii) $6$

$7$ needs $3$ to make $10$; take $3$ from $4$, which leaves $1$.

$4 + 7 = 10 + 1 = 11$

Answer: $\square = 1$; $4 + 7 = 11$

$\square = 9 - 2 = 7$

Check: $2 + 7 = 9$

Answer: $7$

(i) $20 = 10 + 10$ and $10 - 2 = 8$, so $20 - 2 = 10 + 8 = 18$

(ii) $60 = 50 + 10$ and $10 - 2 = 8$, so $60 - 2 = 50 + 8 = 58$

Answer: (i) $18$ (ii) $58$

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

$88 - 7 = 81$

Answer: $81$

1st method: take $1$ out of $2$ first ($2 - 1 = 1$): $11 - 2 = 10 - 1 = 9$

2nd method: add $8$ to both: $11 - 2 = 19 - 10 = 9$

Both methods give $11 - 2 = 9$

Answer: $9$

1st method: take $7$ out of $9$ first ($9 - 7 = 2$): $87 - 9 = 80 - 2 = 78$

2nd method: add $1$ to both: $87 - 9 = 88 - 10 = 78$

3rd method: $87 - 10 = 77$ and $10 - 9 = 1$, so $87 - 9 = 77 + 1 = 78$

All three methods give $87 - 9 = 78$

Answer: $78$

$8$ tens $-$ $5$ tens $=$ $3$ tens

$80 - 50 = 30$

Answer: $30$

1st method (take the tens first): $41 - 16 = 31 - 6 = 30 - 5 = 25$

2nd method: add $4$ to both: $41 - 16 = 45 - 20 = 25$

3rd method: $41 - 20 = 21$ and $20 - 16 = 4$, so $41 - 16 = 21 + 4 = 25$

4th method (column): $1 < 6$, so borrow $1$ ten: units $11 - 6 = 5$, tens $3 - 1 = 2$

All four methods give $41 - 16 = 25$

Answer: $25$

(i) $410 = 400 + 10$ and $10 - 6 = 4$, so $410 - 6 = 400 + 4 = 404$

(ii) units $6 - 1 = 5$, tens $8 - 1 = 7$, hundreds $3$ stays: $386 - 11 = 375$

Answer: (i) $404$ (ii) $375$

1st method (take the tens first): $192 - 25 = 172 - 5 = 170 - 3 = 167$

2nd method: add $5$ to both: $192 - 25 = 197 - 30 = 167$

3rd method: $192 - 30 = 162$ and $30 - 25 = 5$, so $192 - 25 = 162 + 5 = 167$

4th method (column): $2 < 5$, so borrow $1$ ten: units $12 - 5 = 7$, tens $8 - 2 = 6$, hundreds $1$

All four methods give $192 - 25 = 167$

Answer: $167$

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

$100 - 67 = 40 - 7 = 33$

Answer: $33$

1st method (column): units $4 < 8$, borrow $1$ ten: $14 - 8 = 6$

tens: $3 < 7$, borrow from the hundred: $13 - 7 = 6$, hundreds $0$

2nd method: take $4$ from both: $144 - 78 = 140 - 74$

take $40$ from both: $= 100 - 34 = 66$

3rd method: $144 - 100 = 44$ and $100 - 78 = 22$, so $144 - 78 = 44 + 22 = 66$

All three methods give $144 - 78 = 66$

Answer: $66$

$2$ tens $+$ $3$ tens $=$ $5$ tens

$20 + 30 = 50$

Answer: $50$

Tens: $60 + 60 = 120$

Units: $3 + 5 = 8$

$63 + 65 = 120 + 8 = 128$

Answer: $128$

$22 \div 8$: $8 \times 2 = 16$, $22 - 16 = 6$

Bring down $0$, we have $60$: $8 \times 7 = 56$, $60 - 56 = 4$

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

Remainder $0$, so $2200 \div 8 = 275$

Answer: $275$

$2 \div 2$: $2 \times 1 = 2$, $2 - 2 = 0$

Bring down $3$, we have $3$: $2 \times 1 = 2$, $3 - 2 = 1$

Bring down $7$, we have $17$: $2 \times 8 = 16$, $17 - 16 = 1$

Bring down $1$, we have $11$: $2 \times 5 = 10$, $11 - 10 = 1$

Bring down $0$, we have $10$: $2 \times 5 = 10$, $10 - 10 = 0$

Bring down $7$, we have $7$: $2 \times 3 = 6$, $7 - 6 = 1$

Bring down $8$, we have $18$: $2 \times 9 = 18$, $18 - 18 = 0$

Remainder $0$, so $2371078 \div 2 = 1185539$

Answer: $1185539$

$3 \div 3$: $3 \times 1 = 3$, $3 - 3 = 0$

Bring down $2$, we have $2$: $2 < 3$, so write $0$ in the quotient

Bring down $1$, we have $21$: $3 \times 7 = 21$, $21 - 21 = 0$

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

Remainder $0$, so $3219 \div 3 = 1073$

Do not miss the $0$ in the quotient.

Answer: $1073$

$52 \div 12$: $12 \times 4 = 48$, $52 - 48 = 4$

Bring down $4$, we have $44$: $12 \times 3 = 36$, $44 - 36 = 8$

Bring down $4$, we have $84$: $12 \times 7 = 84$, $84 - 84 = 0$

Remainder $0$, so $5244 \div 12 = 437$

Answer: $437$

$\displaystyle \frac{36}{4}$ means $36 \div 4$.

$4 \times 9 = 36$, so $\displaystyle \frac{36}{4} = 9$

Answer: $9$