Questions

Designers stay current by reading magazines, browsing the internet, attending fashion shows, and studying technical manuals. They study the history of fashion to better understand its development and current tendencies.

The logic in the given puzzle is 

4 + 4 = 4 * 4+1 = 4 * 5 = 20

5 + 5 = 5 * 5+1 = 5 * 6 = 30

6 + 6 = 6 * 6+1 = 6 * 7 = 42

7 + 7 = 7 * 7+1 = 7 * 8 = 56

Similarly

9 + 9 = 9 * 9+1 = 9 * 10 = 90.

SDR means Special Drawing Rights.

SDRs are a measure of a country's reserve assets with IMF and, whereas not 'money' in the strict sense, have several characteristics of money as interest-bearing assets, store of value, and means of settling indebtedness.

International financing instrument created in 1970 by the International Monetary Fund (IMF) to coincide with the disfavor of the US dollar as the principal currency of the world trade. Also called paper gold, an SDR is neither paper nor gold but an accounting entry. It is not backed by any currency or precious metal and is used only among governments and IMF for balance Of payments settlements.

The key to this math riddle is realizing that the one place must be zero.
888 +88 +8 +8 +8 =1,000