Chapter 2, Problem 67E

Correct any answers that have the incorrect number of significant figures.

a. $\left(78\cdot 56-9\cdot 44\right)\times 45\cdot 6=3152$

b. $\left(8\cdot 9\times {10}^5÷2\cdot 348\times {10}^2\right)+121=3\cdot 9\times {10}^3$

c. $\left(45\cdot 8÷3\cdot 2\right)-12\cdot 3=2$

d. $\left(4\cdot 5\times {10}^3-1\cdot 53\times {10}^3\right)÷34\cdot 5=86$