Explanation:
1 meter = 1000 mm
the area of 1.6 m² means the side length of the square is
sqrt(1.6) = 1.264911064... m = 1,264.911064... mm
to create a square out of the rectangular pattern he needs to put e.g. 42 patterns along the 45 mm side and stack 45 patterns on top of the 42 mm side.
the minimum number of needed patterns we get via the last common multiple (LCM) of 42 and 45.
for this we use the prime factorization :
45 ÷ 2 no
45 ÷ 3 = 15
15 ÷ 3 = 5
5 ÷ 3 no
5 ÷ 5 = 1
45 = 3² × 5¹
42 ÷ 2 = 21
21 ÷ 2 no
21 ÷ 3 = 7
7 ÷ 3 no
7 ÷ 5 no
7 ÷ 7 = 1
42 = 2¹ × 3¹ × 7¹
the LCM is the product of the longest streaks of each used prime factor.
LCM(42, 45) = 2¹ × 3² × 5¹ × 7¹ = 2×9×5×7 = 630
(i) he needs 210 patterns to form the smallest square.
this will be
14×45 mm on one side = 630 mm
15×42 mm on the other side = 630 mm
14×15 = 210 patterns.
(ii)
the limit per side length is as established
1,264.911064... mm
starting with the minimum of 630 mm how often can we add 42 mm in one direction and 45 mm in the other, and keep a 15 : 14 ratio between these numbers ?
and we need integer numbers, as we cannot use parts of the patterns (only full patterns).
45 × x <= 1264
x <= 1264/45 = 28.08888888... = integer 28
42 × y <= 1264
y <= 1264/42 = 30.0952381... = integer 30
30/28 = 15/14
so, the ratio is maintained for these numbers.
that means as maximum we can put
30×28 = 840 patterns as square inside the max. allowed area.
the dimensions of this max. square are therefore
30×42 = 1260 mm
28×45 = 1260 mm
the area of this square is then
1260mm × 1260 mm = 1,587,600 mm² = 1.5876 m²