number series

[fast trak]

1) 3,6,9,18,21,...?

options are
78, 56, 40, 48, 42

2) 57, 45, 36, 30, 27,...?

options
24, 38, 35, 27, 55

Thanks

[Sally-Anne]

1) 3,6,9,18,21,...?

options are
78, 56, 40, 48, 42

x2, +3, x2, +3, ... x2 ... answer 42

2) 57, 45, 36, 30, 27,...?

options
24, 38, 35, 27, 55

-12, -9, -6, -3, ... -0 ... answer 27

(Three times table, subtract in reverse.)

[fast trak]

thanks a lot

another one

13(18)23 29(24)19

22( ) 6

options
24, 14, 36, 12, 22

[Sally-Anne]

Good thing I'm at a loose end tonight, isn't it? (I shouldn't be, but I can't quite get down to the task in hand ...

13(18)23 29(24)19

22( ) 6

options
24, 14, 36, 12, 22

13 + 23 = 36 / 2 = 18

29 +19 =48 / 2 = 24

22 + 6 = 28 / 2 = 14

If the number in the middle brackets is in between those either side you are probably subtracting, or adding them and halving. (And possibly adding or subtracting a small number beyond that.)

[DC17C]

13 +23 =36/2 =18
29+19=48/2= 24


22+6=28/2=14

[fast trak]

thanks a ton. so many options to remember.

[fast trak]

3(24)18 1(44)22

13( )26

[patricia]

3(24)18 1(44)22

13( )26

18 divided by 3 = 6
How do you get to 24 = x 4 [left number plus 1]

22 divided by 1 = 22
How do you get to 44 = x 2 [left number plus 1]

26 divided by 13 = 2
2 x left number plus 1 [13 plus 1 = 14]
2 x 14 = 28

Patricia

[fast trak]

omg this is too much