Hugo wants to make a sandwich using Wrap (W) or Baguette (B)
and
Cheese (C) or Turkey (T)
and
Mayonnaise (M) or Ketchup (K)
a) List all the possible types of sandwiches Hugo could make.
One has been done for you (write all your answers on one line).
WCM,
b) What fraction of the possible types of sandwich have Turkey and Ketchup?

the largest number of the four options is 1.8 x 10-2

you have it in scientific notation.

1.80 x 10-6   = 0.00000180

1.80 x 10-4   = 0.000180 (bigger, or "less small", than the former one)

so

1.8 x 10-2       = 0.0180. as you see. the "less small", or the biggest one of them all.

as you have negative exponent, it means you are dividing 1.8 by 100 (i.e. moving the dot towards left, two times).

if you had positive exponent for the scientific notation, power of tenths, you would be multiplying times 100 (moving the dot towards right) as below:

1.8 x (10)2 = 180

so. if you have negative exponent in scientific notation, move the dot toward left. if it is positive, toward right as many times the exponent tells you.