Floor Division in Kotlin

TL ; DR:

• The Math.floor() function returns the largest integer less than or equal to a given number:

  println(Math.floor(3.9)) // Output: 3.0
  println(Math.floor(5.2)) // Output: 5.0
  println(Math.floor(7.0)) // Output: 7.0
  

  
  

• We can use this function if we want to compute the integral part of some division (quotient):

  val a = 3
  val b = 7
  
  println(Math.floor(20.0 / a)) // Output: 6.0
  println(Math.floor(b.toDouble() / a)) // Output: 2.0
  

Full lesson:

Remember how we first learn about the division of two integer numbers in primary school?

The quotient is the number of times a division is completed fully, while the remainder is the amount left that doesn't entirely go into the divisor.

Here are some examples:

10 / 2 = quotient 5, remainder 0
15 / 4 = quotient 3, remainder 3
20 / 3 = quotient 6, remainder 2

Floor division

Floor division is a normal division operation except that it returns the integral part of the result (the quotient). In Kotlin there is no separate operator for it: dividing two Int values with / already gives the quotient (the fractional part is dropped):

println(10 / 2) // Output: 5
println(15 / 4) // Output: 3
println(20 / 3) // Output: 6

It can also be used with variables:

val a = 3
val b = 7

println(20 / a) // Output: 6
println(b / a) // Output: 2

Modulo

The modulo operator (%) calculates the remainder of dividing two values:

println(10 % 2) // Output: 0
println(15 % 4) // Output: 3
println(20 % 3) // Output: 2

// Can be used with variables:
val a = 2
val b = 4

println(b % a) // Output: 0
println(11 % b) // Output: 3

Quotient and remainder

In programming, we combine both these concepts to get the quotient and remainder of some divison:

// Let's divide 26 by 3:
val quotient = 26 / 3
val remainder = 26 % 3

println(quotient) // Output: 8
println(remainder) // Output: 2

Assignment
Follow the Coding Tutorial and let's practice with quotient and remainder!

Hint
Look at the examples above if you get stuck.