Rounding Decimal Numbers With Two Decimal Places: Foundation (Year ... - Free Printable

Let's solve the rounding decimal numbers problem step by step.

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Question 1: Rounding to 1 Decimal Place (1 d.p.)

#### Part a) Show the position of these decimal numbers on the number line:
We are given the numbers:
1.61, 1.66, 1.68, 1.63
And the number line ranges from 1.6 to 1.7, divided into 10 equal parts → each small tick is 0.01.

So, positions:
- 1.61 → 1st tick after 1.6
- 1.63 → 3rd tick after 1.6
- 1.65 → 5th tick after 1.6 (already shown)
- 1.66 → 6th tick after 1.6
- 1.68 → 8th tick after 1.6

You would mark each of these on the number line accordingly.

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#### Part b) Round the numbers to 1 decimal place using the number line.

To round to 1 decimal place, we look at the second decimal digit:
- If it’s less than 5, we round down
- If it’s 5 or more, we round up

Let’s go through each:

1. 1.61 → second decimal is 1 (<5) → rounds to 1.6 ✔ (already done)

2. 1.68 → second decimal is 8 (≥5) → rounds up to 1.7

3. 1.66 → second decimal is 6 (≥5) → rounds up to 1.7

4. 1.65 → second decimal is 5 → rounds up to 1.7

5. 1.63 → second decimal is 3 (<5) → rounds down to 1.6

✔ So answers for part 1b:
- 1.61 → 1.6
- 1.68 → 1.7
- 1.66 → 1.7
- 1.65 → 1.7
- 1.63 → 1.6

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Question 2: Rounding to 1 Decimal Place

#### Part a) Show the position of these decimals on the number line:
Numbers: 2.42, 2.48, 2.36, 2.45
Number line from 2.3 to 2.5, divided into 10 parts → each tick = 0.01

Positions:
- 2.34 → already shown (at 4th tick after 2.3)
- 2.42 → 12th tick after 2.3 → 2nd tick after 2.4
- 2.48 → 18th tick after 2.3 → 8th tick after 2.4
- 2.36 → 6th tick after 2.3
- 2.45 → 15th tick after 2.3 → halfway between 2.4 and 2.5

Mark them accordingly.

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#### Part b) Round to 1 decimal place

Use the rule again: look at the hundredths digit (second decimal):

1. 2.34 → hundredths digit is 4 (<5) → rounds down → 2.3 ✔ (already done)

2. 2.45 → hundredths digit is 5 → rounds up → 2.5

3. 2.48 → hundredths digit is 8 (≥5) → rounds up → 2.5

4. 2.36 → hundredths digit is 6 (≥5) → rounds up → 2.4

5. 2.42 → hundredths digit is 2 (<5) → rounds down → 2.4

✔ So answers for part 2b:
- 2.34 → 2.3
- 2.45 → 2.5
- 2.48 → 2.5
- 2.36 → 2.4
- 2.42 → 2.4

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✔ Final Answers:

#### Question 1b):
- 1.61 → 1.6
- 1.68 → 1.7
- 1.66 → 1.7
- 1.65 → 1.7
- 1.63 → 1.6

#### Question 2b):
- 2.34 → 2.3
- 2.45 → 2.5
- 2.48 → 2.5
- 2.36 → 2.4
- 2.42 → 2.4

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🔍 Explanation Summary:

- When rounding to 1 decimal place, look at the second decimal digit.
- If it's < 5, keep the first decimal as-is.
- If it's ≥ 5, increase the first decimal by 1.
- The number line helps visualize where the number lies — if it's closer to the lower number, round down; if closer to the higher, round up.

This method ensures accurate rounding based on proximity to the nearest tenth.