This is a number system which uses a base of 10. the valid digits are 0 to 9.

Decimal system

Step-by-step explanation:

The present system in Mathematics we use for representing numbers is a system which uses a base of 10.

We write 0 to 9 then next value we shift the digit from units to 10th place and write as 10.  Thus we use only digits form 0 to 9, and place values for digits from right are

For less than 1 we use decimals and use place values from right to left as

Thus the system we use now is decimal system which has base 10.

probability for j is 1/4

while

a is 1/6

step-by-step explanation:

the true ones are a b and d