This manual is written to accompany Mathematical Interest Theory by Leslie Jane Federer Vaaler and James W. Daniel. . It includes detailed solutions to the odd-numbered problems. There are solutions to 239 problems, and sometimes more than one way to reach the answer is presented . In keeping with the presentation of the text, calculator discussion for the Texas Instruments BAII Plus or BAII Plus Professional calculators is typeset in a different font from the rest of the text.