Mental Arithmetic 01

1530+1470

• 2500

• 3000

• 2700

• 2900

75+23+42

(a)  

35 x 20

• 350

• 70

• 35

• 700

10-9+8-7+6-5+4-3+2-1

• 1

• 3

• 5

• 7

5 x 4 x 3 x 6

(a)  

The 25% of 240 equals:

• 30

• 60

• 80

• 120

Doubling the double of the triple of 4 equals:

• 24

• 48

• 96

• 120

 $\left(3\times4\div6\right)^2$  

(a)  

4 groups of 30 people each, are reunited to be redistributed in 5 different groups with the same number of members. The number of people to be in each group is:

• 12

• 24

• 36

• 48

A package must be delivered and the price to pay depends on its weight. You must pay $5.000 for packages up to 5 kg., adding $10 per additional 100 g. How much to pay for a package whose weight is 7.5 kg?

• $5250

• $5375

• $5500

• $5875