This is how to do map enlargement and map reduction.

IN REDUCING ANY MAP TO GIVEN SIZE, THE FOLLOWING STEPS SHOULD BE FOLLOWED:

  • Measure the length and width of the map. 
  • Divide the length and width by 2 or 4 if you are asked to reduced the map to half or a fourth of its original size. For example, if the length and width of a map are 24cm and 20cm respectively, such a map should measure 12cm by 10cm if seduced to half its size and 6cm by 5cm if reduced to a fourth of its size and so on.
  • Having reduced the original map, it is obvious that the scale would equally change. Therefore, if a map has a scale of 1:50,000, the scale of the map changes to 1:100,000 if the size has been reduced to half, and 1:200,000 if the size of the map has been reduced to a fourth of its original size.
  • The features to be shown on the reduced map should also be proportional to the required size of the map.
  • When you have finished drawing the reduced map, remember to write its title and the new horizontal scale.

IN ENLARGING ANY MAP THE FOLLOWING STEPS SHOULD BE TAKEN

  • Measure the length and width of the original map.
  • Multiply the length and width by 2 or 4 respectively if you intend to enlarge the map to twice or thrice its original size.For example, if the length and width of a map are 5cm and 3cm respectively, such a map would measure 10cm by 6cm if enlarged to twice its size and 20cm by 12cm if enlarged four times its size and so on.
  • Having enlarged the original map, it is equally obvious that the scale would change. Therefore, if a map has a scale of 1:60,000, the scale of the map changes to 1:30,000 if the size has been enlarged twice and 1:15,000 if the size of the map has been enlarged to four times its original size.
  • The features to be shown on the enlarged map should also be proportional to the required size of the map.
  • When you have finished drawing the enlarged map, write its title and the new horizontal scale.

Before one can know whether to reduce or enlarge a map, it may be necessary to divide the initial scale (scale of the original map) by the scale of the new map to be drawn. For example if the scale of a map is 1:50,000 and is to be reproduced to a scale of 1:200,000, divide the former scale with the latter as follows:
50000/200000=1/4

Therefore the new map should be 1/4 times the size of the original map.

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