Exercise 1 solution

Left line 52, bottom line 08.

Four-figure reference: easting then northing = 5208.

Point 4 tenths across, 9 tenths up:
  easting  = 52 + 4 = 524
  northing = 08 + 9 = 089
  six-figure reference = 524089

Point 0 tenths across, 5 tenths up:
  easting  = 52 + 0 = 520
  northing = 08 + 5 = 085
  six-figure reference = 520085

Note the zero in the middle of each: the tenth digit must always be written,
even when it is 0, or the reference will have the wrong number of figures.