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Lesson # 7 Decimals written as money ! When doing operations with decimals… • Think about MONEY ! How much money is $0.05 a) b) c) d) 5 cents 5 dollars Half a cent Or half a dollar ? If you said… $0.05 is …half a dollar…or half a cent…or 5 bucks……then… I’m sorry… • You are • W R O N G !!!!!!!!!! $0.05 is equal to 5 cents. Another example… • $0.025 is equal to… A) B) C) D) A quarter Two and a half cents Twenty five cents Two dollars and fifty cents. If you said that $0.025 is equal to B) Two and a half cents, then you are right! So… • When adding, subtracting, multiplying or dividing … • Numbers with DECIMALS…. Think about… Cash MONEY An example of adding… $0.015 + 0.015 = ? $0.015 = one and a half cents • Soooooooooo 0.015 + 0.015 equals… • One and a half cents PLUS one and a half cents… • ( 0.03) Three Cents ! An example of subtracting… • $1.25 – $0.05 = ? Think… • $1.25 equals one dollar and twenty five cents… • Subtract… • $0.05 (a nickel) • Therefore $1.25 - $0.05 = $1.2 (One dollar and twenty cents) An example of Multiplying… 0.12 x 2.0 = ? Convert the “friendliest” number into groups and the other to MONEY! 0.12 x 2.0 • Make the 0.12 the money (12 cents) • Make the 2.0 the number of groups That means you have … • Two groups of 12 cents… • Which is 24 cents ( 0.24) ! An example of dividing… • $0.35 ÷ 0.05 = ? Think… 0.35 (35 cents) ÷ 0.05(5 cents) How many times would… • Five cents fit into 35 cents? Seven ? Right ! Lets get ready for 12 practice questions ! • • • • • 12” , That’s right “ 3 add, 3 subtract, 3 multiply and 3 divide. Question # 1 0.1 + 0.01 = ? Question # 2 0.25 – 0.2 = ? Question # 3 0.5 x 3.0 = ? Question # 4 0.35 ÷ 0.05 = ? Question # 5 4.75 + 0.2 = ? Question # 6 1.5 – 0.75 = ? Question # 7 0.08 x 5.0 = Question # 8 1.25 ÷ 0.25 = ? Question # 9 0.025 + 0.25 = ? Question # 10 1.1 – 0.03 = ? Question # 11 25.0 x 0.01 = ? Question # 12 2.25 ÷ 0.25 = ? And now the answers… • Get Ready! Question # 1 0.1 + 0.01 = 0.11 Question # 2 0.25 – 0.2 = 0.05 Question # 3 0.5 x 3.0 = 1.5 Question # 4 0.35 ÷ 0.05 = 7 Question # 5 4.75 + 0.2 = 4.95 Question # 6 1.5 – 0.75 = 0.75 Question # 7 0.08 x 5.0 = 0.4 Question # 8 1.25 ÷ 0.25 = 5 Question # 9 0.025 + 0.25 = 0.275 Question # 10 1.1 – 0.03 = 1.07 Question # 11 25.0 x 0.01 = 0.25 Question # 12 2.25 ÷ 0.25 = 9 The END !