4th grade
posted by dk .
reena says the product of 54 and 9 cannot be 487. she says that she knows this without actually multiplying. how does she know?

what is the last digit of 4x9?
4x9=36, so last digit is 6, which doesnt match last digit in 487.
Another way. The nines divisibility rule: 9 is evenly disible in any number in which the sum of digits is 9. Adding 4,8,7 gives 19, and 9 wont go into that. 
54 * 9 cannot be 487 because 4 * 9 = 36. The ones digit must be 6.
Respond to this Question
Similar Questions

math
4th grade math homework. rounding sums and differences. paper say "round each number to its highest place. then estimate the sum or difference." example says 92 +28= then says round to 90 and 30 to make 120. further down numbers get … 
URGENT: Grade 8 Math
In my math question it says: Multiply. Simplify before multiplying. Use benchmarks to estimate to check the product is resonable. a)3/4 x 8/5 is one of the equations What are benchmarks? 
4th grade math
REASONING Tara says that 1/2 of a salad is always the same amount. Lynn says that it could be different amounts, depending on how large the salad is. Who is correct and why? 
4th grade
How can you show without multiplying that 4/9 is greater than 0.4? 
4th grade
without multiplying, how do you know that the product of 399 and 48 is smaller than 20,722? 
4th grade math
M says that every number in the nineties is composite.J says that one number in the nineties is prime. who is correct? 
4th grade math
Hi! This question says Joe is thinking of o function machine.He says that the output is 12 if the input is 4.what are 2 rules that he could be thinking of for his function machine? 
4th grade...math
It says: Find two numbers the exact answer is between. 6 times 7,381 
Math
Eric and Madison both measured the trading card. Eric says he got 3 inches and Madison says she got 2 3/4th. The teacher says both are right. How is that possible? 
Statistics Math
There are 3 men sitting in a row facing the same way. Their names are A,B, AND, C. a hat has been placed on their heads without them seeing their own or anyone else's. A can see B and C, B can see only C, C sees none. The game goes …