# Anchor without Pants

Some people may want to add why this works (or doesn’t work) but this is an anchor to help students remember where the zero cannot go!

Thank you to the teacher who shared this at a workshop.

This can be supplemented with other examples like 12 cookies divided by no people or count by zeros and you will never get to 12.

# Now and Later: Get/Give 2 Copies of a Review Sheet

A review sheet is a gift and usually a preview of the exam!

if your teacher gives you a review sheet, do not write on it so you will be more likely to REDO the problems.
If you are a teacher, hand out 2 copies and/or post a copy on line so students can redo rather than just reading them over.

Study skills are different for Math than for other content areas…please practice now and then again later 🙂

# October 2015 Brain Teaser Solution

Q: How many squares are on an 8 x 8 checkerboard?  10 x 10? How many rectangles?

8 x 8 There are:
64 1 x 1
49 2 x 2
36 3 x 3
25 4 x 4
16 5 x 5
9  6 x 6
4 7 x 7
1 8 x 8 for a total of 204 squares

For 10 x 10
100 1 x 1
81 2 x 2
64 3 x 3
49 4 x 4
36 5 x 5
25 6 x 6
16 7 x 7
9 8 x 8
4 9 x 9
1 10 x 10

for a total of 385 squares

The rectangle counting is significantly more challenging.

# Student work: How much is 12/0?

G
oogle says Infinity

Now try the calculator from Web 2.0 Calculator
W
eb 2.0 says “Error: Divide by 0”

Desmos says “Infinity”

went through a lot of online calculators until I found this: http://www.calculator-tab.com/.  It says error and also says division by zero is not defined

Wolfram Alpha says “complex infinity”

Try your cell phone calculator(s) and post any other interesting answers here by leaving a comment…this student meant to write Undefined but wrote something super close 🙂

# Brain Teaser Solution September 2015

Q: Find positive integers A, B and C such that 3^A + 5^B + 7^C (3 to the A power + 5 to the B power + 7 to the C) is a perfect square.  What is the smallest perfect square possible?

A: 81 is the smallest perfect square possible

List the powers of 3 5 and 7

3 9 27

5 25 125

7 49 343

If we combine 9 + 25 + 49 = 81