Amiyha's Rounding Reef
Round numbers to the nearest 10, 100, and 1,000!
Three lessons · Step-by-step
Lesson 1
Round to the Nearest 10
Rounding means finding the closest "nice" number. To round to the nearest 10, ask: which 10 is closest? Let's help an axolotl find its way home!
Round 47 to the nearest 10
Step 1 — The axolotl is at 47. The nearest reefs are at 40 and 50.
40
50
47
Step 2 — Look at the ones digit to decide which way to round.
4
7
tens
(rounding here)
(rounding here)
ones
(check this!)
(check this!)
The ones digit is 7.
Step 3 — The rule: if the digit is 5 or more, round UP. If it's 4 or less, round DOWN.
Is 7 5 or more? YES! ✓
So we round UP.
So we round UP.
Step 4 — On the number line, 50 is the closer reef!
40
50 ★
47
47 is only 3 away from 50, but 7 away from 40.
Step 5 — The answer!
47 rounded to the nearest 10 = 50
50 ✓
★ ☆ ★
The Rule: To round to the nearest 10, look at the ones digit.
• If it's 5, 6, 7, 8, or 9 → round UP
• If it's 0, 1, 2, 3, or 4 → round DOWN (stay)
• If it's 5, 6, 7, 8, or 9 → round UP
• If it's 0, 1, 2, 3, or 4 → round DOWN (stay)
"5 or more, raise the score.
4 or less, let it rest."
4 or less, let it rest."
Lesson 2
Round to the Nearest 100
Same idea, just bigger numbers! To round to the nearest 100, look at the tens digit instead of the ones digit.
Round 384 to the nearest 100
Step 1 — The axolotl is at 384. The nearest reefs are at 300 and 400.
300
400
350
384
Step 2 — To round to the nearest 100, look at the tens digit.
3
8
4
hundreds
(rounding here)
(rounding here)
tens
(check this!)
(check this!)
ones
The tens digit is 8.
Step 3 — Is the tens digit 5 or more? 5 or more, raise the score.
Is 8 5 or more? YES! ✓
So we round UP.
So we round UP.
Step 4 — On the number line, 400 is the closer reef!
300
400 ★
384
384 is only 16 away from 400, but 84 away from 300.
Step 5 — The answer!
384 rounded to the nearest 100 = 400
400 ✓
★ ☆ ★
The Rule: To round to the nearest 100, look at the tens digit (the digit just to the right of the hundreds).
Same trick: 5 or more, raise the score. 4 or less, let it rest.
Same trick: 5 or more, raise the score. 4 or less, let it rest.
Lesson 3
Round to the Nearest 1,000
Big numbers, same trick. To round to the nearest 1,000, look at the hundreds digit. The pattern always works — just shift one place to the right.
Round 6,427 to the nearest 1,000
Step 1 — The axolotl is at 6,427. The nearest reefs are at 6,000 and 7,000.
6,000
7,000
6,500
6,427
Step 2 — To round to the nearest 1,000, look at the hundreds digit.
6
4
2
7
thousands
hundreds
(check!)
(check!)
tens
ones
The hundreds digit is 4.
Step 3 — Is 4 five or more? 4 or less, let it rest.
Is 4 5 or more? NO ✗
So we round DOWN (stay).
So we round DOWN (stay).
Step 4 — On the number line, 6,000 is the closer reef!
6,000 ★
7,000
6,427
6,427 is only 427 away from 6,000, but 573 away from 7,000.
Step 5 — The answer!
6,427 rounded to the nearest 1,000 = 6,000
6,000 ✓
★ ☆ ★
The Pattern: No matter what place you're rounding to, look at the digit just to the right.
• Round to nearest 10 → look at the ones digit
• Round to nearest 100 → look at the tens digit
• Round to nearest 1,000 → look at the hundreds digit
• Round to nearest 10,000 → look at the thousands digit
• Round to nearest 10 → look at the ones digit
• Round to nearest 100 → look at the tens digit
• Round to nearest 1,000 → look at the hundreds digit
• Round to nearest 10,000 → look at the thousands digit
"5 or more, raise the score.
4 or less, let it rest."
4 or less, let it rest."