Rounding to the Nearest Ten and Hundred

You'll learn how to simplify numbers by rounding them to the nearest ten or hundred using place value rules.

What Is Rounding?

Rounding means replacing a number with a simpler, nearby number that's easier to work with. Think of it like estimating: if you have 47 apples, you might say "about 50 apples" instead of the exact count.

Rounding to the Nearest Ten

When rounding to the nearest ten, look at the ones place:

• If the ones digit is 0, 1, 2, 3, or 4 → round DOWN (keep the tens digit, make ones = 0)
• If the ones digit is 5, 6, 7, 8, or 9 → round UP (increase the tens digit by 1, make ones = 0)

Examples:

• 43 → Look at 3 (ones place) → 3 is less than 5 → round DOWN to 40
• 47 → Look at 7 (ones place) → 7 is 5 or more → round UP to 50
• 65 → Look at 5 (ones place) → 5 rounds UP → 70

Rounding to the Nearest Hundred

When rounding to the nearest hundred, look at the tens place:

• If the tens digit is 0, 1, 2, 3, or 4 → round DOWN (keep the hundreds digit, make tens and ones = 0)
• If the tens digit is 5, 6, 7, 8, or 9 → round UP (increase the hundreds digit by 1, make tens and ones = 0)

Examples:

• 234 → Look at 3 (tens place) → 3 is less than 5 → round DOWN to 200
• 478 → Look at 7 (tens place) → 7 is 5 or more → round UP to 500
• 850 → Look at 5 (tens place) → 5 rounds UP → 900

Quick Memory Trick

"Five or above, give it a shove (up). Four or below, let it go (down)."

Key Takeaway: Rounding simplifies numbers by looking at the digit to the right of your target place value—if it's 5 or more, round up; if it's 4 or less, round down.