Math 201 Prof. Brick
section 51 Spring 02
Math Elem Ed Exam 2
Do the problems in order in your bluebook. Show your work.
1. Use a block model to illustrate 125 −47. Show and describe any and all steps.
2. Using the fact that 99 is close to 100, describe how you could multiply 99 ·76 quickly.
Explain mathematically why this works.
3. Estimate 62 + 193 + 41 + 119 + 80 + 12. Explain mathematically why this works.
4. Explain in detail how a numberline model with a car handles 6 −(−3).
5. For what values of the digit a is the integer 8747341379332a divisible by 3. What
divisibility test are you using ?
6. Use the Euclidean algorithm to find the g.c.d. of 8532 and 3876. Show each step.
7. Working modulo 12, compute 7 +5 +4 +8 +10. Do not use any calculations in base 10.
8. Factor x2
−100
9. Simplify 28
·253