OTHER FINANCIAL INFORMATION
In addition to our results determined under U.S. generally accepted accounting principles (“GAAP”) discussed above, we believe the following non-GAAP measures are useful to investors in evaluating our operating performance. For the fiscal years ended January 31, 2019, 2018, and 2017, our gross profit, gross margin, (loss) income from operations, operating margin, net (loss) income, diluted net (loss) income per share and diluted shares used in per share calculation on a GAAP and non-GAAP basis were as follows (in millions except for gross margin, operating margin, and per share data):
For our internal budgeting and resource allocation process and as a means to provide consistency in period-to-period comparisons, we use non-GAAP measures to supplement our consolidated financial statements presented on a GAAP basis. These non-GAAP measures do not include certain items that may have a material impact upon our reported financial results. We also use non-GAAP measures in making operating decisions because we believe those measures provide meaningful supplemental information regarding our earning potential and performance for management by excluding certain benefits, credits, expenses and charges that may not be indicative of our core business operating results. For the reasons set forth below, we believe these non-GAAP financial measures are useful to investors both because (1) they allow for greater transparency with respect to key metrics used by management in its financial and operational decision-making and (2) they are used by our institutional investors and the analyst community to help them analyze the health of our business. This allows investors and others to better understand and evaluate our operating results and future prospects in the same manner as management, compare financial results across accounting periods and to those of peer companies and to better understand the long-term performance of our core business. We also use some of these measures for purposes of determining company-wide incentive compensation.
There are limitations in using non-GAAP financial measures because non-GAAP financial measures are not prepared in accordance with GAAP and may be different from non-GAAP financial measures used by other companies. The non-GAAP financial measures included above are limited in value because they exclude certain items that may have a material impact upon our reported financial results. In addition, they are subject to inherent limitations as they reflect the exercise of judgments by management about which charges are excluded from the non-GAAP financial measures. We compensate for these limitations by analyzing current and future results on a GAAP basis as well as a non-GAAP basis and also by providing GAAP measures in our public disclosures. The presentation of non-GAAP financial information is meant to be considered in addition to, not as a substitute for or in isolation from, the directly comparable financial measures prepared in accordance with GAAP. We urge investors to review the reconciliation of our non-GAAP financial measures to the comparable GAAP financial measures included below, and not to rely on any single financial measure to evaluate our business.
Table:
 |  | Fiscal Year Ended January 31, | 
 | 2019 | 2018 | 2017
 |  | (Unaudited) | 
Gross profit | $2,283.9 | $1,753.2 | $1,689.1
Non-GAAP gross profit | $2,317.0 | $1,785.5 | $1,743.2
Gross margin | 89% | 85% | 83%
Non-GAAP gross margin | 90% | 87% | 86%
Loss from operations | $(25.0) | $(509.1) | $(499.6)
Non-GAAP income (loss) from operations | $316.0 | $(112.0) | $(125.5)
Operating margin | (1)% | (25)% | (25)%
Non-GAAP operating margin | 12% | (5)% | (6)%
Net loss | $(80.8) | $(566.9) | $(582.1)
Non-GAAP net income (loss) | $223.3 | $(106.3) | $(111.0)
Diluted net loss per share | $(0.37) | $(2.58) | $(2.61)
Non-GAAP diluted net income (loss) per share | $1.01 | $(0.48) | $(0.50)
GAAP diluted weighted average shares used in per share calculation | 218.9 | 219.5 | 222.7
Non-GAAP diluted weighted average shares used in per share calculation | 222.0 | 219.5 | 222.7


Question: How much did gross margin change from fiscal year ending January 31, 2019 compared to the prior year?
Answer: 4
Calculation: 89%-85%