Write the number in standard notation 6.43 x 10 ^-4

Can someone 50 first drop menu 0.80 or 0.75 or 1.20 or 4.00 second drop menu 4.00 or 0.75 or 0.25 or 3.75 3rd 15,6,10, or 9 4th yes or no

Your client has saved $1,860 for a down payment on a house. a government loan program requires a down payment equal to 3% of the loan amount. what is the largest loan amount that your client could receive with this program

Ling listed all of the factors of a mystery number: 1,2,4,8,16,32 what is the mystery number?