This is yet another example of why I believe in giving number sense concepts nicknames. And once again, the solution is probably quicker than reading the title. This concept showed up 15 times this year on high school tests--almost always between questions 21 & 25, inclusive. I mentioned a couple of days ago that this skill is my personal favorite--it tends to come with the brightest "light bulb" moments when I teach it.
Note: You may want to review Square11-20 and Square21-30 in conjunction with this lesson.
Number Dojo Level: 169
This is the easiest of several different questions about adding squares. Look for problems where one of the numbers is three times the other, such as:
I usually hesitate to show the proofs behind these skills, because when you take a number sense test, I don't want you wasting time thinking about the math behind the math. I want you to solve the problems as quickly as you can (which is why I created this blog). But this one is so cool, I want you to know the background. Here goes:
- Realize this is an AddSquareTrip problem (because the bigger number is 3 times the smaller).
- Square the smaller number.
- Add a zero at the end.
- You are done. (Why are you still reading this?)