Find the values of the expressions: a) 5,31 · 10, 0,23 · 10, 4,3 · 10, 0,1 · 10, 0,02 · 10; b) 5,431 · 100, 30,45 · 100, 0,009 · 100, 0,24 · 100, 0,1 · 100, 0,02 · 100; c) 78,71 · 1000, 5,4 · 1000, 0,00039 · 1000, 0,009 · 10000, 0,203 · 10000.

Solution:

• To find the values of the expressions, we multiply the numbers by 10, 100, or 10000. When multiplying a decimal by a power of 10, we move the decimal point to the right by the number of zeros in the power of 10.

Calculations:

• a)
• 5,31 \(\times\) 10 = 53,1
• 0,23 \(\times\) 10 = 2,3
• 4,3 \(\times\) 10 = 43
• 0,1 \(\times\) 10 = 1
• 0,02 \(\times\) 10 = 0,2
• b)
• 5,431 \(\times\) 100 = 543,1
• 30,45 \(\times\) 100 = 3045
• 0,009 \(\times\) 100 = 0,9
• 0,24 \(\times\) 100 = 24
• 0,1 \(\times\) 100 = 10
• 0,02 \(\times\) 100 = 2
• c)
• 78,71 \(\times\) 1000 = 78710
• 5,4 \(\times\) 1000 = 5400
• 0,00039 \(\times\) 1000 = 0,39
• 0,009 \(\times\) 10000 = 90
• 0,203 \(\times\) 10000 = 2030

Final Answer:

a) 53,1; 2,3; 43; 1; 0,2

b) 543,1; 3045; 0,9; 24; 10; 2

c) 78710; 5400; 0,39; 90; 2030