GRADE 8 MENTAL MATH - 3

Instructions:

Grab pencil and paper. In a column, list the numbers 1 to 10.

Calculators are not allowed. All calculations must be done in your head and not on paper!

QUESTIONS

1) Simplify this expression:

2) Find a simplified algebraic expression for the perimeter of an equilateral triangle in which each side measures 2x + 1 cm.

3) What is the sum of the exterior angles of a decagon?

4) What is the numerical value of ?

5) The rule of a transformation is: ( x, y ) g ( x, y – 2 ). Find the image coordinates of (–8, 5)?

6) The area of a circle sector is one third the area of the circle. What is the measure of the central angle of this sector?

7) The circumference of a circle is meters. What is the length of the radius?

8) Using H for Heads and T for Tails, list the 4 possible outcomes if we toss 2 coins only once.

9) If 80% of the tickets sold in a lottery say "Sorry, try again" -- what is the probability of winning a prize?

10) Which numbered triangle is the image of the shaded triangle after a refection in the y-axis? (write triangle 1, 2 or 3 for your answer)

Solutions

 1) 9x + 3 2) 6x + 3 3) 360° 4) 8 5) ( – 8, 3 ) 6) 120° 7) r = 5 m 8) HH, HT, TH, TT 9) 20% or 1 in 5 10) triangle 3