Steve Yegge’s “five essential phone-screen questions” contains lots of good advice about phone screens. In particular, I love how even the simplest questions have basically unlimited possibilities for exploration.

For example, taking his multiplication table question, I could ask a candidate to take in the size of the table as an argument. Once that’s done, they could calculate the maximum size of a table entry, for formatting. Then they could present the user with a random quiz question before showing the table.

Just for fun, here’s my sample answer to this extended question.

``````import math
import random
import sys

LEFT_SPACES = 2

a, b = random.randint(1, n), random.randint(1, n)
answer = input("{} * {} = ".format(a, b))
if a * b == int(answer):
print("Correct!\n")
else:
print("Not quite. Check the table!\n")

def printTable(n):
pad = LEFT_SPACES + 1 + math.floor(math.log(n*n, 10))
fmtstr = '{:>' + str(int(pad)) + '}'
for i in range(1,n+1):
for j in range(1,n+1):
print(fmtstr.format(i*j), end='')
print()

n = 12
if len(sys.argv) >= 2:
n = int(sys.argv[1])

printTable(n)
``````

And a sample run:

``````\$ ./multTable.py 15

10 * 15 = 150
Correct!

1    2    3    4    5    6    7    8    9   10   11   12   13   14   15
2    4    6    8   10   12   14   16   18   20   22   24   26   28   30
3    6    9   12   15   18   21   24   27   30   33   36   39   42   45
4    8   12   16   20   24   28   32   36   40   44   48   52   56   60
5   10   15   20   25   30   35   40   45   50   55   60   65   70   75
6   12   18   24   30   36   42   48   54   60   66   72   78   84   90
7   14   21   28   35   42   49   56   63   70   77   84   91   98  105
8   16   24   32   40   48   56   64   72   80   88   96  104  112  120
9   18   27   36   45   54   63   72   81   90   99  108  117  126  135
10   20   30   40   50   60   70   80   90  100  110  120  130  140  150
11   22   33   44   55   66   77   88   99  110  121  132  143  154  165
12   24   36   48   60   72   84   96  108  120  132  144  156  168  180
13   26   39   52   65   78   91  104  117  130  143  156  169  182  195
14   28   42   56   70   84   98  112  126  140  154  168  182  196  210
15   30   45   60   75   90  105  120  135  150  165  180  195  210  225
``````