These six self-checking riddles focusing on rounding to the nearest 10 and 100 are a great resource for classwork, centers, or homework. My kids love doing riddles like these (though I think what they love even more is telling me how corny the jokes are). I, of course, love being able to quickly grade an entire stack of papers!
Common Core State Standards for Mathematics addressed:
Numbers and Operations in Base Ten (NBT)
• Use place value understanding to round whole numbers to the nearest 10 or 100. (3.NBT.1)
• Use place value understanding to round multi-digit whole numbers to any place. (4.NBT.3)
• 6 self-checking puzzles
• answer key for each puzzle
There are three types of puzzles, with each type repeated once. The first three puzzles ask students to round numbers to the nearest 10, and the second three puzzles (formatted just like the first three) require students to round numbers to the nearest 100. I have found that my students have an easier time rounding to the highest place (e.g., round 79 to the nearest 10 or 356 to the nearest 100), than they do when rounding to a place other than the highest one (e.g., round 452 to the nearest 10). Knowing this, I chose the numbers so the puzzles will build in a progressive manner. The first puzzle has students round to the nearest 10, and the tens place is the highest place. The second puzzle mixes numbers with ten as the highest place and hundreds as the highest place, still with students rounding to the nearest 10. In the third puzzle, there are numbers that extend through the thousands place, with students still having to round to the nearest 10. The second set of three puzzles, which require students to round to the nearest 100, are designed to follow the same pattern: puzzle four uses numbers for which the hundreds place is the highest place, puzzle five mixes numbers for which hundreds and thousands are the highest places, and puzzle five uses numbers that extend through the ten thousands place.
The progressive nature of the puzzles allows you to differentiate for varied needs within your math class. If you have some students that are still building their proficiency with rounding, those students can work on the puzzles that require rounding to the highest place while the other students tackle puzzles that ask them to round to places other than the highest. Alternatively, you might have some students work with just the puzzles that ask them to round to the nearest 10 while the other students work on puzzles that require them to round to the nearest 100.
Looking for more practice with rounding whole numbers? Check out:
Rounding the World - rounding whole numbers task cards & printables (set a)
For more self-checking puzzles, please check out:
Self-checking Math Riddles – Reasonableness of Sums/Differences
FREE self-checking mixed numeral/improper fraction puzzle set
I hope your students enjoy these resources and are able to build their proficiency with rounding. – Dennis McDonald