Estimation – Round Whole Numbers using Place Value . Rounding is a strategy to make an approximation of larger numbers or to make numbers easier to manage. Rounding can be done to any place value. Rounding relates to the concept of unitising. Unitising is when a particular place value is chosen as the unit and a number is considered as a multiple of this place e.g. rounding a number to the nearest hundred would create a number that is a multiple of 100. . The number to the right of the place cho