Estimate sums and differences by rounding to the nearest 10 and 100. Also, solve an addition problem by decomposing and regrouping numbers.

The estimated answer is $\boxed{\text{110}}$.

b) $137 - 56$

The estimated answer is $\boxed{\text{80}}$.

2. Use rounding to the nearest 100 to estimate the answers:

a) $589 - 213$

The estimated answer is $\boxed{\text{400}}$.

b) $621 + 273$

The estimated answer is $\boxed{\text{900}}$.

3. Anna must add 583 and 294. Help her by filling in the missing numbers:

The completed calculation is:

4. Calculate the answers, then use the opposite operation to check:

a) $189 - 47$

The answer is $\boxed{\text{142}}$.

b) $632 + 179$

The answer is $\boxed{\text{811}}$.

5. Mrs Mafaya's eggs:

Mrs Mafaya gave away $\boxed{\text{112 eggs}}$.

6. Flow diagram:
The flow diagram shows: Input $\rightarrow \times 5 \rightarrow \text{Output} \rightarrow +3 \rightarrow \text{Final Output}$
The question implies the rule is $\times 5$ then $+3$.

a) Write the rule for this flow diagram in words.
The rule is: Multiply the input number by 5, then add 3.

b) Use the flow diagram to fill in the missing values in the table:

• For input 1: $(1 \times 5) + 3 = 5 + 3 = 8$
• For input 2: $(2 \times 5) + 3 = 10 + 3 = 13$
• For input 3: $(3 \times 5) + 3 = 15 + 3 = 18$
• For input 4: $(4 \times 5) + 3 = 20 + 3 = 23$
• For input 5: $(5 \times 5) + 3 = 25 + 3 = 28$ The completed table is: Input number: 1, 2, 3, 4, 5 Output number: $\boxed{\text{8}}$, $\boxed{\text{13}}$, $\boxed{\text{18}}$, $\boxed{\text{23}}$, $\boxed{\text{28}}$

7. Fill in the missing numbers in the spidergram:
The rule is: Add 2, then multiply by 3. So, $(n + 2) \times 3$.

• For input 1: $(1 + 2) \times 3 = 3 \times 3 = 9$
• For input 2: $(2 + 2) \times 3 = 4 \times 3 = 12$
• For input 3: $(3 + 2) \times 3 = 5 \times 3 = 15$
• For input 5: $(5 + 2) \times 3 = 7 \times 3 = 21$
• For input 10: $(10 + 2) \times 3 = 12 \times 3 = 36$ The missing numbers are $\boxed{\text{9}}$, $\boxed{\text{12}}$, $\boxed{\text{15}}$, $\boxed{\text{21}}$, $\boxed{\text{36}}$.