Students can extend their knowledge of decimal multiplication and square numbers into this activity. Use it as an intro to radicals, an enrichment for multiplication, even a "how to use a calculator to find..." or "how to round a number" lesson. Totally up to you!! There are two versions- maybe one to complete together, and one to complete alone.
If kids are struggling with this, you could point out the diagonal pattern of square numbers in multiplication chart.
All answers will be irrational numbers